4 instructions, int32x4.trunc_f32x4_{s,u},
int32x4.trunc_f64x2_{s,u}_zero.

Drive-by cleanup to wasm-interpreter to use saturated_cast.

The machine ops are named <int>Trunc<float>, dropping the "sat" since
these don't do any saturation anymore.

Bug: v8:12284
Change-Id: I2d4d6a61b819b287fee69e3eea03dd3151cfa10d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3223166Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77598}