[arm] Add formatting helpers for disassembly

Add a new option to disassembler NEON size encoded in instructions with
two registers, 'size2. Rename the current only to 'size3.

Clean up existing operations to use this new formatting option.

Bug: v8:11074
Change-Id: Ie309d93d24602439c3293c8bbfd6c2ecbc9fdfb7
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2575786Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71670}