This CL removes some deprecated sandbox APIs and introduces new ones, in
particular IsSandboxInitialized and GetSandboxReservationSizeInBytes. In
additon, this CL also adds comments to the various public methods of the
Sandbox class.

Bug: v8:10391
Change-Id: If5c3081a0b9f7f192966150a0d2716099357363a
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/+/3647362Reviewed-by: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Samuel Groß <saelo@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80544}