Replace old regression translation and execution tests with .wast tests (#1580)

* add new .wast tests

* invoke "if.only-then.diverging" test case

* add another regression test from #838

* add regression .wast tests from 2nd audit

* add more regression .wast tests

* add more fuse-cmp .wast tests

* remove old non-.wast fuzz and audit tests

All of the ones that are still valid have been converted to .wast tests.

Author: Robbepop