[llvm] [CodeGen] Add MachineRegisterClassInfo analysis pass (PR #120690)

[Diana Picus via llvm-commits]

rovka wrote:

RegisterClassInfo already has a pass-like interface (`runOnMachineFunction`) - could we just change it into a proper pass instead of adding MachineRegisterClassInfo as a wrapper?

https://github.com/llvm/llvm-project/pull/120690