[Codegen/NewPM] Add Function -> MachineFunction adaptor

[aeubanks]

The codegen pipeline should work on a function and its corresponding machine function before moving onto the next function. This is only possible with a function -> machine function adaptor, which we don't currently have (see TODO here)

To get the machine function for a given function in a function pass (the adaptor), we'll need the function analysis manager to handle machine functions, as opposed to a module analysis handling it. That's basically this discourse discussion

@paperchalice @arsenm