Rough skeleton of a "Query" dashboard panel

Summary: Ref T4986. This isn't pretty/usable yet (I need to move rendering out of ListController classes and into SearchEngine classes, I think) but does pull the correct results.

Test Plan:

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T4986

Differential Revision: https://secure.phabricator.com/D9007