Add new opcode numbers for relaxed-simd opcodes as in:
https://github.com/WebAssembly/relaxed-simd/pull/61, and updates
for decoded opcodes larger than two bytes.

Bug: v8:12284
Change-Id: I0bff22812243a39599bfeee3c0bc69171dd3c7d2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3625835Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Deepti Gandluri <gdeepti@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80432}