We introduce simple escape analysis for wasm-gc objects, where struct
allocations that are only assigned to are eliminated. Handling phi uses
of allocated objects is left for future work.

Bug: v8:11510
Change-Id: Ibd0b220466546e150b26b02890572a5174c6872d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3229744Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Manos Koukoutos <manoskouk@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77515}