[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:

@bgra8 Reduced to 
```cpp
template<typename T> 
struct A
{
    template<typename U> 
    auto f(U u) -> decltype(operator=(u));
};

template struct A<void>;
```
Seems like `f` is being set as invalid without any diagnostic... I think I can fix this quickly

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