Before, import and export wrappers were cached based on their
signature. This change
- makes wrapper canonicalization consistent with that of types and
  call_indirect signatures under --wasm-type-canonicalization,
- removes the last uses of signature maps, which will enable us to
  remove them in a future CL.

Change-Id: I512bc234f0ae10e50bd94237e8e675ca47ed13c5
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3891250
Commit-Queue: Manos Koukoutos <manoskouk@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/main@{#83183}