[clang] [clang][ASTMatcher] Add matchers for isExplicitObjectMemberFunction() (PR #84446)

[Balazs Benics via cfe-commits]

steakhal wrote:

Thanks for the prompt review @PiotrZSL!
I plan to merge it by the end of the day, unless someone objects.

https://github.com/llvm/llvm-project/pull/84446