When ArrayBufferExtensions are enabled, sweep the extensions outside of
the GC pause concurrently to the application. The following GC will make
sure that the previous concurrent sweep operation is finished.

This CL introduces Heap::array_buffer_sweeper() that is both
responsible for tracking all extensions but also for sweeping.

Bug: v8:10064
Change-Id: I113cd625445a7d59ffb7a9de8b25a15a72b02b99
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2010107Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65984}