Add pause_processing Management Command

[avrohomgottlieb]

Context

In Issue #1563, requirements were gathered on how to gracefully terminate and recreate jobs upon redeploy.

The conclusion was to:

• Query for all processing jobs
• Terminate those jobs
• Clone those jobs and save their state as JobStates.PENDING

This will ultimately allow for those jobs to be re-submitted by the submit_processing command, which runs every 30 minutes as a cron job.

Problem or idea

A management command should be written, called pause_processing, which implements this command.

A further issue will address how this command is integrated into the deploy sequence.

Solution or next step

• Add management command pause_processing which calls Job::terminate_processing and then Job::create_retry_jobs on the returned terminated jobs
• Add tests