AVX has 3-operands shuffle/unpack operations. We currently always
require that dst == src0 in all cases, which is not required if we have
AVX. For the arch shuffles that map to a single native instruction, add
support to check for AVX in the instruction-selector, to not require
same as first, and in the code-gen to support generating AVX.

The other arch shuffles are slightly more complicated, and can be
optimized in a future change.

Bug: v8:11270
Change-Id: I25b271aeff71fbe860d5bcc8abb17c36bcdab32c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2591858Reviewed-by: Bill Budge <bbudge@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71820}