Implement f64x2, i64x2, i8x16 splats on arm and arm64.

Bug: v8:9909
Change-Id: I41f635ae5c6f025ece7f6445a58fbad1ad678fbd
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2087694Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66616}