This CL adds functionality to read the source positions directly
from the JS heap rather than from serialized data.

In order to do this, we create a PersistentHandles container in the
OptimizedCompilationInfo which gets passed onto the JSHeapBroker. This
allows us to create the handles in the main thread and pass them safely
to the background thread.

In order to read safely from the background thread, we need a LocalHeap
which blocks the GC from running and potentially moving the handles.
This LocalHeap is created only when the JSHeapBroker has finalized
serializing and destroyed when retiring it.

Bug: v8:7790
Change-Id: I19f8b08d12e5be0a3df34d6af2043310c0c7b6fe
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2277802Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68836}