Add "--pool" and "--duration" flags to daemon CLI tools
- Ran bin/phd debug task --pool 4 and got an autoscaling pool.
- Ran bin/worker flood --duration 3 and got some 3-second-long tasks to execute with bin/worker execute ....
Reviewed By: chad
Maniphest Tasks: T12331
Differential Revision: https://secure.phabricator.com/D17431