[clang] [clang] Be const-correct with all uses of `Module *`. (PR #93493)

[Matheus Izvekov via cfe-commits]

mizvekov wrote:

I could agree on being const correct here, but mostly by removing const, not adding more, in the general case.

The problem here is that this is such a big code base, and where some times parameters can be passed down from function to function for a very long depth, that this can make some seemingly small local changes propagate into a lot of code churn.

https://github.com/llvm/llvm-project/pull/93493