[clang] [Clang][Sema][Parse] Delay parsing of noexcept-specifiers in friend function declarations (PR #90517)

[Erich Keane via cfe-commits]

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

Corentin's request for a comment makes sense to me, or perhaps a better name th an just 'D'?  So please take care of his request, but otherwise LGTM.

https://github.com/llvm/llvm-project/pull/90517