Implement ranking for shortcuts.

- Manifest shortcuts are closest to the original icon, in rank order,
  followed by dynamic shortcuts in rank order.
- Also prevent pinned shortcuts from showing in container if they
  aren't also dynamic (only manifest and dynamic show in container).

Bug: 29822383
Bug: 29946657
Change-Id: I5cdb2ef3700daedca01987f64c245beb3f4aa5ee