S390 [simd]: optimize vector multiply extend on codegen

Implantation now includes using a combination of
multiplly even and odd flowed by a vector merge low or high.

vector merge instructions are also added to the simulator.

Change-Id: I144c5d07e5e6bd978788a70aacabd61463f93289
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2815562


Commit-Queue: Milad Fa <mfarazma@redhat.com>
Reviewed-by: Junliang Yan <junyan@redhat.com>
Cr-Commit-Position: refs/heads/master@{#73868}