This is a reland of commit 49c59678

The non-deterministic snapshot issue has been fixed by using the correct
field size for CodeDataContainers in serializer.cc.

Original change's description:
> [sandbox] Fold V8_SANDBOXED_EXTERNAL_POINTERS into V8_ENABLE_SANDBOX
>
> Now that all external pointers have been sandboxed,
> V8_SANDBOXED_EXTERNAL_POINTERS is no longer needed. This change also
> shrinks external pointer slots to 32 bits when the sandbox is enabled.
>
> Bug: v8:10391
> Change-Id: Iccbef27ac107b988cb23fe9ef66da6fe0bae087a
> Cq-Include-Trybots: luci.v8.try:v8_linux64_heap_sandbox_dbg_ng,v8_linux_arm64_sim_heap_sandbox_dbg_ng
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3869269
> Reviewed-by: Leszek Swirski <leszeks@chromium.org>
> Reviewed-by: Manos Koukoutos <manoskouk@chromium.org>
> Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
> Reviewed-by: Igor Sheludko <ishell@chromium.org>
> Commit-Queue: Samuel Groß <saelo@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#83083}

Bug: v8:10391
Change-Id: I29870404406902d99ba6016c570cc0c4d05c6c85
Cq-Include-Trybots: luci.v8.try:v8_linux64_heap_sandbox_dbg_ng,v8_linux_arm64_sim_heap_sandbox_dbg_ng
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3887899Reviewed-by: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Reviewed-by: Manos Koukoutos <manoskouk@chromium.org>
Commit-Queue: Samuel Groß <saelo@chromium.org>
Cr-Commit-Position: refs/heads/main@{#83130}