[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)

[Krystian Stasiowski via cfe-commits]

sdkrystian wrote:

@yxsamliu The type of `this` is always a pointer. The class member access operator may only be overloaded for operands of class type. In your reduced example, could you provide a value of `T` that would instantiate to a valid specialization?

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