[clang] [APINotes] Upstream Sema logic to apply API Notes to decls (PR #78445)

[Egor Zhdan via cfe-commits]

egorzhdan wrote:

Apologies for the delay!
I looked into this performance hit, and it seems largely expected to me: the compiler spends extra time checking if there is an apinotes file for a given clang module with the notes for the declarations that are being processed. We can consider adding a Clang driver option to disable API Notes, if this performance regression is significant enough.

https://github.com/llvm/llvm-project/pull/78445