This CL adds a v8_allocation_site_tracking flag to control the allocation and
tracking of memento objects.

Disables FLAG_allocation_site_pretenuring if v8_allocation_site_tracking
is disabled.

v8_enable_single_generation implies !v8_allocation_site by default.

Change-Id: Ib07528bd37d91de6bb6ea0bfea1699be4e17fae9
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2897326
Commit-Queue: Wenyu Zhao <wenyu.zhao@anu.edu.au>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74879}