Identify *.MODULE.bazel files as Starlark

[rafikk]

Bazel 7.2.0 introduced the ability to include the contents of another "MODULE.bazel-like" file in MODULE.bazel. These files must be suffixed with ".MODULE.bazel" and should be identified as Starlark, just like the root MODULE.bazel file.

Checklist:

• I am adding a new extension to a language.
  • The new extension is used in hundreds of repositories on GitHub.com
    • Search results for each extension:
      • https://github.com/search?q=path%3A*.MODULE.bazel+NOT+is%3Afork&type=code&ref=advsearch
  • I have included a real-world usage sample for all extensions added in this PR:
    • Sample source(s):
      • https://github.com/bazel-contrib/rules_img/blob/2da48912fb41aaf6afa4580b44a0f791541113fe/e2e/cc/toolchain.MODULE.bazel#L133
    • Sample license(s): Apache 2.0
  • I have included a change to the heuristics to distinguish my language from others using the same extension.

[rafikk]

Hi @lildude. Thanks for taking a look and unblocking the CI checks. I believe with the latest set of changes, the checks should be passing now.

I see you've added the "Pending Popularity" label to this PR. What is the threshold for getting this change merged? The checklist say "hundreds of repositories" and search shows 175 public files (though I'm not sure in how many unique repositories). I assumed that >100 repositories would qualify. Is there a more specific threshold?

[lildude]

I assumed that >100 repositories would qualify. Is there a more specific threshold?

linguist/CONTRIBUTING.md

Lines 79 to 80 in 347e912

	In most cases we prefer that each new file extension be in use in at least 200 unique `:user/:repo` repositories before supporting them in Linguist
	(but see [#5756][] for a temporary change in the criteria).