Slightly improve saved query UX

Summary:
Ref T2625.

  - Show saved queries in the left nav.
  - Highlight the correct stuff in the left nav.

Test Plan: Clicked all left-nav stuff.

Reviewers: btrahan, blc

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T2625

Differential Revision: https://secure.phabricator.com/D6053