With this CL we add proposal tests to the wasm-spec-tests. For this I
extended the update-wasm-spec-tests.sh script. Additionally to
generating the spec tests it does the following:

For each proposal it identifies those tests that are different to the
spec tests, and then copies those tests also to the wasm-spec-tests
directory.

Additionally I adjusted the test runner of the wasm spec test to
run the proposal tests with the correct flags.

CC=binji@chromium.org
R=clemensh@chromium.org

Bug: v8:7581
Change-Id: Idb7aa3c0a468ddb65b2ef3421def836561579cd9
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1706470Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62777}