[clang] [clang-tools-extra] Reapply "[Clang][Sema] Diagnose class member access expressions naming non-existent members of the current instantiation prior to instantiation in the absence of dependent base classes (#84050)" (PR #90152)

[via cfe-commits]

dyung wrote:

> @zmodem Fixed in [3191e0b](https://github.com/llvm/llvm-project/commit/3191e0b52725aa17651e38d26284386f3ea64eb6)

This change also seems to fix the small example I posted, I'll double check it against our original source code.

https://github.com/llvm/llvm-project/pull/90152