Move Drydock object list rendering to SearchEngine

Summary: Ref T4986. Allows the Drydock search engines to render as panels.

Test Plan: Viewed affected interfaces in Drydock. Created panels from each engine.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T4986

Differential Revision: https://secure.phabricator.com/D9103