The CL introduces F16x8Splat, F16x8ExtractLane and F16x8ReplaceLane
opcodes together with software implementation in Liftoff.

Bug: 337998764
Change-Id: I628d25feba492afe02d4f4d325e4aaf824a98d53
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/5722510


Commit-Queue: Ilya Rezvov <irezvov@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/main@{#95137}