This CL moves a few methods and nested class SlotSnapshottingVisitor
from ConcurrentMarkingVisitor to ConcurrentMarkingVisitorUtility.

Methods in ConcurrentMarkingVisitorUtility are now static and instead have a Visitor parameter.

This is preparatory work for adding a
YoungGenerationConcurrentMarkingVisitor class, which will be able to
reuse members of ConcurrentMarkingVisitorUtility.

Bug: v8:13012
Change-Id: I503c20e655578031018a2e37dd92c1d61bbe1686
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3779677
Commit-Queue: Leon Bettscheider <bettscheider@google.com>
Reviewed-by: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/main@{#81931}