copt arguments that include spaces don't work with MSVC

### Description of the bug:

When compiling a C++ program with Bazel, `--copt="-D FOO"` works for gcc and clang, but not for MSVC.

### 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.

1. On a Windows machine with MSVC installed, clone https://github.com/bazelbuild/examples
2. Replace the contents of `examples/cpp-tutorial/stage1/main/hello-world.cc` with

```c
#ifdef FOO
#pragma message("FOO is defined!")
#else
#pragma message("FOO isn't defined :(")
#endif
int main() { return 0; }
```

4. Observe that `bazel build --copt="-D FOO" ...` prints "FOO isn't defined :("

---

Note that all of these commands correctly print "FOO is defined!":
- `bazel build --copt="-DFOO" ...`
- `bazel build --copt="-D FOO" --compiler=clang-cl ...`
- `cl.exe -D FOO main/hello-world.cc`

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

Windows 11 Pro

### 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.

_No response_

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

_No response_

### 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?

No

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

_No response_

Start with the minimal reproduction in examples/cpp-tutorial/stage1/main/hello-world.cc and run the reported bazel build --copt="-D FOO" command on Windows with MSVC. Trace how Bazel passes spaced --copt arguments to MSVC, then verify the build prints "FOO is defined!" while preserving the working gcc and clang behavior.

Written by the indexing model from the issue text.