WS-412: Run multiple jobs at a time

In this MR:

• Request status pages now open in new tabs to make it easier for multiple job submissions
• wf_monitor now runs as a non-blocking subprocess, allowing the system flow to continue uninterrupted by job submission
• Added logging to capability_queue.py

Issues brought up by this MR that are yet unfixed:

1. Occasionally, the delivery message for a request is not triggered by the workflow-complete message
2. Executions that are queued beyond the concurrency limit seem to be lost and never executed, possibly due to engines not looking for new executions once freed