[clang] [clang-format] Add common attribute macros to Google style (PR #76239)

[Owen Pan via cfe-commits]

owenca wrote:

> `GUARDED_BY` and `ABSL_GUARDED_BY` are very commoon in Google codebases so it is reasonable to include them by default to avoid the need for extra configuration in every Google repository.

I don't feel comfortable with this as it might impact users of the Google style with non-Google codebases. @mydeveloperday @HazardyKnusperkeks @rymiel can you chime in?

https://github.com/llvm/llvm-project/pull/76239