Introduce common bottleneck for all incremental marking step
invocations from a task context. This will later be used to move
code out of IncrementalMarking::Step.

This is a reland of https://crrev.com/c/3822682. This CL now always
schedules normal tasks instead of delayed ones in order to keep current
behavior.

Bug: v8:11708
Change-Id: I0dc378879177458a6429ea0b3acd3ee45b499240
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3833814Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82486}