Bug fixes for widget picker search.

SearchBarController
- Use Extended Edit Text to handle close keyboard action well.
- On press enter while search remove focus from bar and hide keyboard.
- On cancel button press hide keyboard and also reset search targets to empty so that on next search session the previous results dont flash (show for a short time before reflecting users query).

WidgetsFullSheet
- Make sure expanded header are reset when user leaves personal/work recycler views. Search recycler view resets its expanded header on every search already.
- Show 'no search results' view if no search result present.
- Update WidgetListBaseRowEntryComparator to show personal profile widgets first.

Test: Tested prototype locally.
Bug: b/157286785
Change-Id: Ibaa208c4091783e14ac0887caf559e867185df5a