This is a reland of commit 76a07814

Changes compared to original:
- Add WasmArray::SetTaggedElement, which uses write barriers.
- In Factory::NewWasmArrayFromElementSegment, the new array may have
  moved to OldSpace until it is initialized. Therefore, it needs write
  barriers; use the new method for that.
- Small readability improvements.

Original change's description:
> [wasm-gc] Implement array.init_from_elem
>
> Bug: v8:7748
> Change-Id: I65dbb496302045820063bd0f4f9ea054e6a645bd
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3695580
> Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
> Commit-Queue: Manos Koukoutos <manoskouk@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#81128}

Bug: v8:7748
Change-Id: Ic5def1886f662bddce72b8eaea274eb5e8ec0c68
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3704513Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Manos Koukoutos <manoskouk@chromium.org>
Cr-Commit-Position: refs/heads/main@{#81196}