New layout for widget picker is still not up to
final design, but this change prepares all the
backend work
Also, remove use of features filter from the
picker, since this is being removed from the API
Change-Id: I9b332e22cf34b98c20c720602c920d28aed01d6c
Bug: 2325451.
This change also improves the UI by returning an empty drawable of the appropriate
size to make sure all labels line up correctly in the list.
