[RISCV] Add a pass to merge moving parameter registers instructions for Zcmp

This patch adds a pass to generate `cm.mvsa01` & `cm.mva01s`.

RISCVMoveOptimizer.cpp which combines two mv inst into one cm.mva01s or cm.mva01s.

Reviewed By: craig.topper

Differential Revision: https://reviews.llvm.org/D150415