[cleanup][wasm-c-api] Drop custom binary reader/writer

The code to create wrapper modules on the fly was dead already.
The code to read wire bytes has been replaced with accesses to
V8's internal decoded form of the same data.

Change-Id: I736c8467df3ded9de08f2d567dbfd5e695dcfb0e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1698384
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62691}