R1:32890594522b

Unify "toggle buttons" controls

Summary: This control is a very thin shell right now with Maniphest/Differential
code duplication; unify the implemenations better for use in Audit.

Test Plan: Clicked toggle buttons in Differential and Maniphest.

Reviewers: btrahan, jungejason

Reviewed By: btrahan

CC: aran, epriestley

Differential Revision: https://secure.phabricator.com/D1700