Support autoscaling daemons in phd

Summary: Ref T7352. This supports passing autoscaling configuration to daemons, and adds debug --autoscale.

Test Plan: See D11711.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T7352

Differential Revision: https://secure.phabricator.com/D11860