Motivation:
There were three versions of type decoding for wasm in the codebase.
Not all of them decoded gc types with immediates (reference types)
correctly.

Changes:
- Refactor the wasm binary decoder for unify type decoding.
- Update BranchTypeImmediate and SelectTypeImmediate to handle
  reference types.

Reference: https://github.com/WebAssembly/gc

R=jkummerow@chromium.org
Bug: v8:7748

Change-Id: I33b38c911d366570ca6ef2723ded5205698e1979
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2179003
Commit-Queue: Manos Koukoutos <manoskouk@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67614}