[clang] [clang][ast][objc] Implement getNameForDiagnostic for ObjCMethodDecl and ObjCPropertyDecl. (PR #213030)

[Balázs Benics via cfe-commits]

https://github.com/steakhal commented:

> My understanding is that improving diagnostic messages is encouraged, and maintenance of any downstream tooling depending on them for regex parsing is up to the developer of such tooling :)

You are right. The PR looks good.

I want to lear more about your motivation. What made you writing this patch?

https://github.com/llvm/llvm-project/pull/213030