[clang] [attributes][-Wunsafe-buffer-usage] Support adding unsafe_buffer_usage attribute to struct fields (PR #101585)

[Artem Dergachev via cfe-commits]

https://github.com/haoNoQ approved this pull request.

Aha great, this is exactly how I imagined it would look like! We might need some more boilerplate though.

+Erich for attributes.

https://github.com/llvm/llvm-project/pull/101585