This CL introduces a compile flag v8_enable_inner_pointer_resolution_mb.
Behind it, it introduces a method `FindBasePtr` in `MemoryChunk`, which
implements inner pointer resolution using the chunk's marking bitmap.
This method is intended to be used for conservative stack scanning, to
resolve inner pointers to heap objects, at some point late in the
marking phase.

It also delays stack scanning during the marking phase of a full GC, to
ensure that marking has proceeded and most heap objects have already
been marked.

Bug: v8:12851
Change-Id: I40e291a86bb8d2587a2c1d9505574dde3c65eb16
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3703837
Commit-Queue: Nikolaos Papaspyrou <nikolaos@chromium.org>
Reviewed-by: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#81404}