dependencies: add "active" jobs dependency #807
Description
One of the limits we had discussed potentially adding in last week's meeting was a limit on the number of jobs in multiple active states; more specifically, those jobs in SCHED, RUN, and CLEANUP. This would encompass more jobs than just those that are running, but also allow for more granular control than limits on just "active" jobs, which are tracked as they enter job.new. The other potential benefit to using a dependency for this kind of limit would be to actually hold the job instead of rejecting it outright, which is how the max_active_jobs dependency is enforced.
@ryanday36 do you have any thoughts here? Could a limit like this be useful for clusters with a lot of traffic?