[clang] [clang-tools-extra] thread-safety: Support the new capability-based names for all related attributes. (PR #99919)

[Pierre d'Herbemont via cfe-commits]

pdherbemont wrote:

> Thank you for these changes! Can you also add a release note to `clang/docs/ReleaseNotes.rst` so users know about the new attribute spellings?

They are already sort of documented as such – but will update the ReleaseNotes.rst.

Does anyone know why the new names were documented but not actually implemented?

https://github.com/llvm/llvm-project/pull/99919