This CL introduces a new XX1-Form instruction as well as
separates VX-Form instructions to be used for implementing
simd Splat:

- I32x4
- I8x16
- I16x8

Change-Id: If81bbc87b45993ba6fa3e0146dd34496e247dd50
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2165866Reviewed-by: Junliang Yan <jyan@ca.ibm.com>
Commit-Queue: Milad Farazmand <miladfar@ca.ibm.com>
Cr-Commit-Position: refs/heads/master@{#67393}