[clang] [APINotes] Refactor APINotesReader to propagate llvm::Error (PR #183812)

[Gábor Horváth via cfe-commits]

https://github.com/Xazax-hun approved this pull request.

This is good to go now. Do you have commit access or do you need someone to hit the merge for you?

https://github.com/llvm/llvm-project/pull/183812