Move cancel/retry/free task queue actions to bin/worker
Summary:
Fixes T6702. Ref T3554. Currently, tasks can be cancelled, retried and freed from the web UI by any logged in user.
This isn't appreciably dangerous (I can't come up with a way that a user could do anything security-affecting), but I think I probably intended this to be admin-only, but these actions should move to the CLI anyway.
Move them to the CLI. Lay some groundwork for some future bin/worker cancel --class SomeTaskClass, but don't implement that yet.
Test Plan: Used cancel, retry and free from the CLI. Hit all the error/success states.
Reviewers: btrahan
Reviewed By: btrahan
Subscribers: epriestley
Differential Revision: https://secure.phabricator.com/D10939