Changes:
- Implement WasmExportedFunction::MatchesSignature.
- Use it over comparison with == in ResolveWasmImportCall.
- Add a test which exposes the existing bug.
- Add a few reminder TODOs.

Bug: v8:9495
Change-Id: Ibbe31dbf550be212dbf2170ab8cdab9b4b6de734
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2438060
Commit-Queue: Manos Koukoutos <manoskouk@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70215}