Bug 1617827 - Wasm: Switch to 'wasm-generate-testsuite' tooling for importing spec test-suite. r=lth

This switches our test import Makefile to use the wasm-generate-testsuite tool
for importing spec-tests. A new config file declaring the proposals to import,
along with tests to skip, is added to jit-test/etc.

There was an ability to apply a .patch file to paper over a back-compat issue
is types.wast.js. It appears that newer spec/tests don't include a types.wast,
so I don't think this patch is necessary anymore. We can add this ability back
later if needed.

Differential Revision: https://phabricator.services.mozilla.com/D65195

--HG--
extra : moz-landing-system : lando