R1:f38a565aa5b6

Use radio buttons with explanatory text to select commit rule types

Summary: Ref T4264. Instead of a dropdown, make this step more informative.

Test Plan: {F93928}

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T4264

Differential Revision: https://secure.phabricator.com/D7846