Implement "Sort by Points" on workboards

Summary: Depends on D20275. Fixes T10578. This is a static sorting (like "By Date Created") where you can't change point values by dragging. You can still drag cards between columns, or use the "Edit" icon to change point values.

Test Plan: {F6265191}

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T10578

Differential Revision: https://secure.phabricator.com/D20276