Also move Pshufb definition into shared-macro-assembler. We define a
Pshufb that handles both SSE and AVX, and in SSE case will move src to
dst if they are not the same.

Define operator== and operator!= in ia32's Operand class that will check
against XMMRegister, we can then use DCHECK_NE to ensure that a register
doesn't alias a operand wrapping a register.

Bug: v8:11589
Change-Id: I7c30881e8a9b322b736bb7301dde0c5424efacdd
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3119997
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/main@{#76515}