Allow tasks to be searched by subtype
Ref T12314. Allow tasks to be queried by subtype using a typeahead.
Open to a better default icon. I'll probably let you configure them later.
Just hide this constraint if there's only one subtype.
- Searched for subtypes.
- Verified that the control hides if there is only one subtype.
Reviewed By: chad
Maniphest Tasks: T12314
Differential Revision: https://secure.phabricator.com/D17444