[clang-tools-extra] [include-cleaner] Report refs for enum constants used through namespace aliases (PR #106706)

[Ilya Biryukov via cfe-commits]

https://github.com/ilya-biryukov approved this pull request.

LGTM. See a small suggestion about adding another test too.

https://github.com/llvm/llvm-project/pull/106706