[clang] [clang-tools-extra] [clang] Extend diagnose_if to accept more detailed warning information (PR #70976)

[Erich Keane via cfe-commits]

https://github.com/erichkeane commented:

I'm a little cold on review here, so I don't want to accept this, but I did a scroll through and don't have any problems here.  Additionally, a bunch of whitespace changes are still in this, which is making it difficult tor eview.

https://github.com/llvm/llvm-project/pull/70976