On x64 we can emit more compact instructions for mov(reg, imm). However
currently this only happens when using the Set method explicitly.
This CL renames Set to Move to avoid confusion and yield better code
by default.

Also use the new Move helper for Smis as well.

Change-Id: I06558e88d1142098f77fb98870f09742d494f3dc
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2874450Reviewed-by: Zhi An Ng <zhin@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74512}