[RISCV] SFB with Immediates to QC.MVccI (#186555)
When we are just branching over a move (rather than a more complex
instruction), then Xqcicm sometimes has equivalent conditional move
instructions for that which are shorter.
We can only turn `qc.b<cc>i` instructions into `qc.mv<cc>i` instructions
because the immediate ranges match (5-bit). The `qc.e.b<cc>i` take
larger immediates (16-bit) for which there is no equivalent.
