Include scanning hints support

### Description of the feature request:

One of the features of include scanning that is implemented internally at google, but not implemented externally, is the concept of a "hints" file. This file allows you to add extra files that are required by an action even if they don't match the regex. This allows users to solve the case like:

```
#define FOO "foo.h"
#include FOO
```

I would like to submit a PR for support with this feature (or if google wants to export their internal version that would be fine too)

Currently the include scanning flag docs say:

> Use at your own risk. Any issues relating to this flag that are filed will be closed. At Google without this flag your build will most likely fail.

So I know this had some history of not being supported and I wanted to file an issue before I submitted the PR

### Which category does this issue belong to?

_No response_

### What underlying problem are you trying to solve with this feature?

_No response_

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

_No response_

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

_No response_

### 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 HEAD` ?

```text

```

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

_No response_

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

_No response_

Start by locating Bazel's include-scanning implementation and the documentation for the include-scanning flag. Determine how a hints file should be specified and consumed for macro-based includes such as the FOO example, then define coverage and documentation updates that demonstrate the feature works.

Written by the indexing model from the issue text.