The more complicated subtyping checks due to the new wasm-gc types
caused a performance regression. This CL:
- Adds a V8_LIKELY annotation to the more common path
  (type equality).
- Factors the rest of the check out of the inlinable part of subtype
  checking to reduce binary size, and thus cache misses.

Bug: chromium:1096769, v8:7748
Change-Id: Idd92789b40cc175c268ef5a53f042d4b881992af
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2263156
Commit-Queue: Manos Koukoutos <manoskouk@chromium.org>
Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68511}