This change removes the subtyping between funcref and anyref.
Currently, nullref (ref null none) is still a subtype of funcref and externref.
This has to be adapted in a follow-up change introducing nullexternref
(ref null noextern) and nullfuncref (ref null nofunc).

Bug: v8:7748
Change-Id: I77a1b3fef387faf710f7bf7bf9d4655fb600ffdc
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3804253Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Matthias Liedtke <mliedtke@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82267}