Extract AllocationCounter (which manages the allocation observers) out
of Space and pass it on initialization.
AllocationCounter will instead be a field of the subclasses (e.g.
PagedSpace, NewSpace).
This will allow to reuse the same AllocationCounter for the NewSpace and
PagedSpaceBase parts of PagedNewSpace (crrev.com/c/3641178).

Bug: v8:12612
Change-Id: Ie6ed10d1b138a5724cf9b469ab9c943518850ad4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3745403
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#81524}