Implement a lint count query

Summary: Ref T2683. This query is currently unbatched and happens inside a view. Leave it inside the view for now, but separate it and make it batchable.

Test Plan: {F34848}

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley, vrana, aran

Maniphest Tasks: T2683

Differential Revision: https://secure.phabricator.com/D5252