Introduce JSGlobalObjectRef to the heap broker.

Bug: v8:7790
Change-Id: I055a0545b582d6ff4c4e0dd639ce532311a76fec
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1773267Reviewed-by: Georg Neis <neis@chromium.org>
Commit-Queue: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63472}