Daemons - introduce PhabricatorWorkerArchiveTaskQuery

Summary: Ref T5402. This cleans up some code and sets us up to use this sort of data more easily later.

Test Plan: viewed the daemon console from the web and the log of a specific archived daemon. both looked good. for other callsites looked really, really carefully.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T5402

Differential Revision: https://secure.phabricator.com/D11042