Changes:
- Wrap eqref and i31ref objects in the temporary wasm object wrapper
  (in addition to dataref and anyref). Accept those types in
  IsJSCompatibleSignature().
- Handle null correctly in all cases (i.e., do not wrap/unwrap it).
- Improve some error messages.
- Handle kRttWithDepth in one case where it was omitted.
- Some small structure improvements.
- Add an extensive test.

Bug: v8:7748, v8:11606
Change-Id: Ie519f2c87421664dd02cf29fe94f9a9d7510bae2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2794422
Commit-Queue: Manos Koukoutos <manoskouk@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#73725}