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

[via cfe-commits]

yronglin wrote:

> > This means that no macros of any kind can appear in the module name.
> 
> Exactly. This is why the grammar in the wording is defined in terms of `pp-token` and not `identifiers`: no macro expansion takes place at all.

Thanks! Let's use `LexUnexpandedToken` during parsing module name.

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