This splits WeakObjects into explicit global and local worklists.
The latter are defined in WeakObjects::Local and are thread-local.

The main thread local worklist is stored in
MarkCompactCollector::local_weak_objects and exists during marking
similar to local_marking_worklists. Concurrent markers create their
own local worklists that are published at the end.

Change-Id: I093fdc580b4609ce83455b860b90a5099085beac
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2440607
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70317}