[llvm] [CodeGen] Port PrintMIR to new pass manager (PR #79440)

[Arthur Eubanks via llvm-commits]

aeubanks wrote:

the legacy pass collects the strings from `printMIR(MachineFunction &)` on all machine functions in `runOnMachineFunction()`, then in `doFinalization()` it runs `printMIR(Module &)` and then dumps the collected machine function prints

that sort of matches what we do in here/NewPMDriver.cpp where we first run the module pass manager then the machine function pass manager, but we're taking the output of `printMIR(Module &)` before the machine function passes have run, whereas the legacy version takes the output of the module after machine function passes have run. is there going to be an issue with that?

https://github.com/llvm/llvm-project/pull/79440