[wasm-gc] Experiment: accept types with explicit inheritance

This patch makes V8 accept the binary format produced by Binaryen
after https://github.com/WebAssembly/binaryen/pull/3933 when the
--experimental-wasm-gc-experiments flag is present. The explicit
inheritance information is not used for anything. Validation is
performed only insofar as explicit supertypes must be valid types.

Bug: v8:7748
Change-Id: Id5b5050aa03591281632e3a2a161aa93422e10bd
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3071406


Reviewed-by: Manos Koukoutos <manoskouk@chromium.org>
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#76135}