This implements the rest of the load extend instructions:

- i32x4.load16x4_s
- i32x4.load16x4_u
- i64x2.load32x2_s
- i64x2.load32x2_u

Bug: v8:9886
Change-Id: I4649f77bae5224042a1628d9f0498c050b1e599d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1903812Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Bill Budge <bbudge@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65017}