Mostly i16x8 ops, this should complete all i16x8 ops.

Bug: v8:9561
Change-Id: I73515c3c38a5a055ac00f97ba5c363df1bf3c771
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2111711Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66897}