[clang] [Clang] Implement P3034R1 Module Declarations Shouldn’t be Macros (PR #90574)

[Davide Italiano via cfe-commits]

dcci wrote:

> This is clearer, I think I may have figured out where the problem is.

^ I have a reproducer that's running through `creduce`. It should be ready tomorrow morning PST time, and I'll add you here. In the meanwhile, do you mind if I revert this given we understand it breaks several cases so we can get our services building again? It affected many codebases.

https://github.com/llvm/llvm-project/pull/90574