This is a reland of 90a9d6cb

The original CL got reverted because of two different issues:

* The DCHECK failure on AllowGarbageCollection::IsAllowed() got fixed
  in https://crrev.com/c/3289625.
* The crash with the incremental marking job were because of a nested
  GC started from a SafepointScope. This CL adds IgnoreLocalGCRequests
  scopes to SafepointScopes in src/heap.

In addition this CL prevents shared GCs during isolate deserialization
by locking the clients_mutex_ until the isolate is fully deserialized.
The original GC used a DisallowSafepoints scope to prevent shared GCs
from interrupting isolate deserialization.

Original change's description:
> [heap] Support multiple clients in shared GC
>
> Add support for safepointing multiple isolates as described in the
> design doc (link is below). A safepoint across multiple isolates is
> considered a global safepoint to distinguish it from regular safepoints.
>
> The basic idea behind the implementation is that we reach a
> safepoint for each client. What's new is that now also main threads
> need to participate in the safepointing protocol and need to give up
> control in time. The slow paths of Park(), Unpark() and Safepoint() on
> the main thread need to be adjusted for this reason as well.
>
> This CL introduces GlobalSafepoint and GlobalSafepointScope to mirror
> IsolateSafepoint and IsolateSafepointScope.
>
> This CL adds the type IgnoreLocalGCRequests, it is used to prevent
> Park() and Unpark() from honoring the request from background threads
> to perform a local GC. This is used heap-internally to not have GCs
> (or even nested GCs) in certain locations. E.g. when initiating a
> safepoint to perform a GC we don't want a "recursive" GC to occur.
>
> Design doc: https://docs.google.com/document/d/1y6C9zAACEr0sBYMIYk3YpXosnkF3Ak4CEuWJu1-3zXs/edit?usp=sharing
>
> Bug: v8:11708
> Change-Id: I5aca8f5f24873279271a53be3bb093fc92a1a1eb
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3009224
> Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
> Reviewed-by: Jakob Gruber <jgruber@chromium.org>
> Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#77812}

Bug: v8:11708, v8:12375, v8:12377
Change-Id: I9d1af6fbc06a3a8b6f216ec5e9027665ad071809
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3283067
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78013}