Jobs Status command

[tomjn]

I've a site with lots of cavalcade jobs that have been piling up into the thousands because a runner was misconfigured. Now I've some failed jobs, lots of duplicate jobs, etc, and I don't know the true scale of how many jobs there are, just that the runner is now using up all CPU trying to crunch through the backlog

Something like this would be super useful:

> wp cavalcade jobs --status
Running: 4
Waiting: 10
Failed: 5