[llvm] [PassManager] Drop Function.h and Module.h includes (NFC) (PR #96892)

[Nikita Popov via llvm-commits]

nikic wrote:

Turns out this doesn't really do anything, because the headers still get pulled in by Analysis.h, and dropping them from there is significantly more involved. Still going to merge this to clarify that this header doesn't need them.

https://github.com/llvm/llvm-project/pull/96892