[clang-tools-extra] [run-clang-tidy.py] Add -directory-filter option to run-clang-tidy.py (PR #89302)

[Piotr Zegar via cfe-commits]

https://github.com/PiotrZSL requested changes to this pull request.

Personally I do not see use case for it, as source-filter also apply to directories, and better would be to just change source-filter to accept list of regexes.

Other thing that directory-filter works as "exclude", not "include", and for me this could be just --exclude-files or something like that, but still users may use negative regexp.

Release notes change missing.

https://github.com/llvm/llvm-project/pull/89302