Swipe to dismiss suggestions

- Move dismiss suggestion logic into feature provider
- In DashboardData, use hashcode as suggestion's stable id. This is much
  more likely to provide a truely stable id for each suggestion card.
  Eventually I want to use hash for all tiles to provide stable id.
- Add a SuggestionDismissionController to handle swipe to dismiss
  callbacks

Change-Id: If3770f07a90c5469a0b86fc28f3eb5e4c17227cd
Fix: 35159816
Test: make RunSettingsRoboTests