PPC: [wasm][tests] Add proposal tests to the wasm spec tests

Port cd34523b

Original Commit Message:

    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.

R=ahaas@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com
BUG=
LOG=N

Change-Id: Ia976d8017cacb61b46fe076c39ade6bc6137b7e9
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1708989Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Milad Farazmand <miladfar@ca.ibm.com>
Cr-Commit-Position: refs/heads/master@{#62853}

test/wasm-spec-tests/wasm-spec-tests.status

@@ -47,6 +47,8 @@
   'tests/f64': [SKIP],
   # This test fails because ppc float to double doesn't convert sNaN to qNaN.
   'tests/conversions': [SKIP],
+   'tests/proposals/reference-types/conversions':  [SKIP],
+   'tests/proposals/bulk-memory-operations/conversions': [SKIP],
 }],  # 'arch == ppc or arch == ppc64'
 
 ['arch == s390 or arch == s390x', {