This CL takes advantage of the z15 `load byte reverse element`
instruction to optimize Simd LoadExtend opcodes.

On the simulator we only run `load element` as reversing is
not required.

Change-Id: Ia34ac86f93e987656596b3116771a30f64009416
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3119048Reviewed-by: Junliang Yan <junyan@redhat.com>
Commit-Queue: Milad Fa <mfarazma@redhat.com>
Cr-Commit-Position: refs/heads/main@{#76517}