[clang] [clang-format] Add an fnmatch-like function for .clang-format-ignore (PR #76021)

[Emilia Kond via cfe-commits]

https://github.com/rymiel approved this pull request.

Are we going to use this specific implementation on all platforms for parity?
The logic on its own looks good as far as I can tell, but, for example, POSIX Section 2.13 mentions that a leading period (hidden files) isn't matched by `*`.
This sort of divergence from the strict POSIX spec is fine in my opinion, just confirming we won't cause parity issues.

https://github.com/llvm/llvm-project/pull/76021