[maglev] Emit parallel moves at ends of blocks

Defer reg->reg moves at end-of-block Phi resolution, and resolve them as
parallel moves using a recursive algorithm with cycle detection.

Bug: v8:7700
Change-Id: I74b9e451775595e6ec3bf1ca2f50e483b876f204
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3487992
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79291}