[APINotes] Upstream dependencies of Sema logic to apply API Notes to decls

This upstreams more of the Clang API Notes functionality that is
currently implemented in the Apple fork:
https://github.com/apple/llvm-project/tree/next/clang/lib/APINotes

This is the largest chunk of the API Notes functionality in the
upstreaming process. I will soon submit a follow-up patch to actually
enable usage of this functionality by having a Clang driver flag that
enables API Notes, along with tests.