[llvm-branch-commits] [RISCV] Port PushPopOpt to NewPM (PR #235507)

[Aiden Grossman via llvm-branch-commits]

https://github.com/boomanaiden154 created https://github.com/llvm/llvm-project/pull/235507

Standard NewPM pass porting. Also note that we preserve the CFG in the
Legacy version of the pass.