Add kWasmS128 to the list of supported types, and implement Fill for all
the architectures so that LocalGet works.

Add a new test file to contain tests that run only on Liftoff, and
assert that the code is indeed compiled by Liftoff.
We cannot rely on the nooptimization variant for testing
because by default, if Liftoff compilation fails, it will fall back to
Turbofan, and we accidentally get a test passing.

We skip these tests on mips architecture that don't support SIMD, since
there is no way to implement these, and we don't have a "lowering" phase
for Liftoff.

As we implement more of SIMD in Liftoff, we can add more
tests to this file and ensure correctness. Future patches will introduce
support for globals and params.

Bug: v8:9909
Change-Id: I7fc911f2d588d60c709ddb258b2efc1f22805fab
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1999470
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65768}