[clang] [clang] Add clang::preferred_type attribute for bitfields (PR #69104)

[Aaron Ballman via cfe-commits]

https://github.com/AaronBallman commented:

The changes should also come with a release note, but I'm generally happy with the code. I did have some suggestions for changes to documentation though.

https://github.com/llvm/llvm-project/pull/69104