Add support for system shortcuts in popup container

- Currently the system shortcuts are just widgets and app info
- As shortcuts, they live in ShortcutsItemView
- They are populated either as icons only (if there are deep
  shortcuts) or as icons + text
- Widgets are disabled until binding them is complete (we request for
  them to be bound on long-press now). We should revisit this.

Bug: 34940468
Change-Id: Ia51d002c3b3ede87658bdab57abfc3eeca1ed242