C++ header validation fails for MSVC remote compile

### Description of the bug:

When building a `cc_library` that includes header files on Windows using an MSVC toolchain with remote execution, I get this error:

```
ERROR: C:/users/jay/code/engflow-example/cpp/BUILD:1:10: Compiling cpp/main.cc failed: undeclared inclusion(s) in rule '//cpp:cpp':
this rule is missing dependency declarations for the following files included by 'cpp/main.cc':
'C:/_b/gjo2whp5/execroot/ws/cpp/hello.h'
```

### Which category does this issue belong to?

C++/Objective-C Rules

### What's the simplest, easiest way to reproduce this bug? Please provide a minimal example if possible.

You will need a remote execution service with Windows that can execute actions in containers. I think that makes this difficult to reproduce, though maybe Google has something internally that might work? I'm working on this at EngFlow.

Assuming you have that:

1. Checkout https://github.com/EngFlow/example/pull/243
2. `bazel build --config=remote_windows_x64 //cpp:cpp_lib` (add `--remote_executor` and any other necessary flags).

### Which operating system are you running Bazel on?

Windows Server 2022

### What is the output of `bazel info release`?

release 6.3.2

### If `bazel info release` returns `development version` or `(@non-git)`, tell us how you built Bazel.

n/a

### What's the output of `git remote get-url origin; git rev-parse master; git rev-parse HEAD` ?

```text
n/a
```

### Is this a regression? If yes, please try to identify the Bazel commit where the bug was introduced.

No.

### Have you found anything relevant by searching the web?

Issue [#9172](https://github.com/bazelbuild/bazel/issues/9172) - Windows: Bazel cannot share cpp cache between two projects with different workspace name

PR [#9188](https://github.com/bazelbuild/bazel/pull/9188) - Windows: Ignore workspace name differences while doing header checking

PR [#13339](https://github.com/bazelbuild/bazel/pull/13339) - Remote: Use execRoot as input root and do NOT set working directory by default.

### Any other information, logs, or outputs that you want to share?

I spent the morning poking through the source code to figure out how this works. It looks like Bazel's `CppCompile` action is trying to validate that 1) headers included from `srcs` are in either `srcs` or direct dependencies' `hdrs`, and 2) headers are not included with absolute paths.

For MSVC, Bazel accomplishes that by enabling the `/showincludes` flag, which tells MSVC to print the path of each included file. The paths are absolute. The full output from one of these actions looks like this:

hello.cc

Note: including file: C:\worker\work\2\execroot\ws\cpp/hello.h

Note: including file:  C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\string

Note: including file:   C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\yvals_core.h

Note: including file:    C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\vcruntime.h

Note: including file:     C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\sal.h

Note: including file:      C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\concurrencysal.h

Note: including file:     C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\vadefs.h

Note: including file:    C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\xkeycheck.h

Note: including file:   C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\xstring

Note: including file:    C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\iosfwd

Note: including file:     C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\yvals.h

Note: including file:      C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\ucrt\crtdbg.h

Note: including file:       C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\ucrt\corecrt.h

Note: including file:       C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\vcruntime_new_debug.h

Note: including file:        C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\vcruntime_new.h

Note: including file:      C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\crtdefs.h

Note: including file:      C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\use_ansi.h

Note: including file:     C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\cstdio

Note: including file:      C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\ucrt\stdio.h

Note: including file:       C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\ucrt\corecrt_wstdio.h

Note: including file:        C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\ucrt\corecrt_stdio_config.h

Note: including file:     C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\cstring

Note: including file:      C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\ucrt\string.h

Note: including file:       C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\ucrt\corecrt_memory.h

Note: including file:        C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\ucrt\corecrt_memcpy_s.h

Note: including file:         C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\ucrt\errno.h

Note: including file:         C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\vcruntime_string.h

Note: including file:       C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\ucrt\corecrt_wstring.h

Note: including file:     C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\cwchar

Note: including file:      C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\ucrt\wchar.h

Note: including file:       C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\ucrt\corecrt_wconio.h

Note: including file:       C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\ucrt\corecrt_wctype.h

Note: including file:       C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\ucrt\corecrt_wdirect.h

Note: including file:       C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\ucrt\corecrt_wio.h

Note: including file:        C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\ucrt\corecrt_share.h

Note: including file:       C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\ucrt\corecrt_wprocess.h

Note: including file:       C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\ucrt\corecrt_wstdlib.h

Note: including file:       C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\ucrt\corecrt_wtime.h

Note: including file:       C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\ucrt\sys/stat.h

Note: including file:        C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\ucrt\sys/types.h

Note: including file:     C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\xstddef

Note: including file:      C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\cstddef

Note: including file:       C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\ucrt\stddef.h

Note: including file:       C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\xtr1common

Note: including file:      C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\cstdlib

Note: including file:       C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\ucrt\math.h

Note: including file:        C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\ucrt\corecrt_math.h

Note: including file:       C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\ucrt\stdlib.h

Note: including file:        C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\ucrt\corecrt_malloc.h

Note: including file:        C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\ucrt\corecrt_search.h

Note: including file:        C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\limits.h

Note: including file:      C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\initializer_list

Note: including file:    C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\xmemory

Note: including file:     C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\cstdint

Note: including file:      C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\stdint.h

Note: including file:     C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\limits

Note: including file:      C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\cfloat

Note: including file:       C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\ucrt\float.h

Note: including file:      C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\climits

Note: including file:      C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\intrin0.h

Note: including file:       C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\intrin0.inl.h

Note: including file:      C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\isa_availability.h

Note: including file:     C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\new

Note: including file:      C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\exception

Note: including file:       C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\type_traits

Note: including file:       C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\ucrt\malloc.h

Note: including file:       C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\vcruntime_exception.h

Note: including file:        C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\eh.h

Note: including file:         C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\ucrt\corecrt_terminate.h

Note: including file:     C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\xatomic.h

Note: including file:     C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\xutility

Note: including file:      C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\utility

Note: including file:   C:\Program Files (x86)\Microsoft Visual Studio\2019\BuildTools\VC\Tools\MSVC\14.29.30133\include\cctype

Note: including file:    C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\ucrt\ctype.h

This line is the one that matters:

```
Note: including file: C:\worker\work\2\execroot\ws\cpp/hello.h
```

This is not hermetic. The path of the execroot could be anything. Here's it's `C:\worker\work\2\execroot\ws`. Normally it would be `C:\worker\work\2\exec`, but I've hacked it in this build to try and work around the issue (no luck).

In [ShowIncludeFilter](https://github.com/bazelbuild/bazel/blob/c24b847322e7e21de10a9031aaae19a691475909/src/main/java/com/google/devtools/build/lib/rules/cpp/ShowIncludesFilter.java#L40), Bazel uses a regular expression to replace everything up to `.*execroot\\` with `../`, so that turns into `../ws/cpp/hello.h`. Later, that's joined with the local execroot within the workspace, so `C:/_b/gjo2whp5/execroot/ws/cpp/hello.h`, which is the path we see in the error message.

Bazel expects the path to be `C:/_b/gjo2whp5/execroot/example/cpp/hello.h` (`example` is the name of the workspace). Because it does not match, Bazel reports an error.

Tagging @meteorcloudy and @coeuvre who I think might have ideas on how to fix this. I'd be happy to work on this, but I'll need some guidance on what the solution should be and whether there's a good way to test it.

Start by tracing Bazel's CppCompile action and its MSVC /showincludes header-validation handling, focusing on how remote execution maps absolute execroot paths. Reproduce with the EngFlow example PR and the stated remote Windows build command; done means the declared cpp/hello.h dependency is recognized without relying on the worker's absolute path.

Written by the indexing model from the issue text.