Move completed tasks to an "archive" table and delete them in the GC
Summary:
Currently, when taskmasters complete a task it is immediately deleted. This prevents us from doing some general things, like:
- Supporting the idea of permanent failure (e.g., after N failures just stop trying).
- Showing the user how fast taskmasters are completing tasks.
- Showing the user how long tasks took to complete.
Having better visibility into this is important to Drydock, which builds on the task system. Also, generally buff debug output for task execution.
Test Plan: Ran bin/phd debug taskmaster. Ran bin/phd debug garbage. Queued some tasks via various systems.
Reviewers: btrahan
Reviewed By: btrahan
CC: aran
Maniphest Tasks: T2015
Differential Revision: https://secure.phabricator.com/D3852