[llvm] [CodeGen] Let `PassBuilder` support machine passes (PR #76320)

[Arthur Eubanks via llvm-commits]

aeubanks wrote:

at a high level, I think it makes sense to consolidate handling machine passes into PassBuilder

however, it's unfortunate that this cements the Passes -> CodeGen dependency. it would be great if people could use PassBuilder to only run IR passes without pulling in all of CodeGen. but if `MachineFunction` is part of CodeGen, we can't really avoid that dependency

https://github.com/llvm/llvm-project/pull/76320