Add a "Customize Query" action to query panels to make it easier to make minor query adjustments

Summary:
Depends on D20473. Ref T13272. Fixes T7216. If you want to tweak the query a panel uses, you currently have to complete 7 Great Labors.

Instead, add a "Customize Query" action which lets you update the query inline.

Test Plan:

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T13272, T7216

Differential Revision: https://secure.phabricator.com/D20474