Add recommendation setting and remove app settings

- Add a new setting to control whether smartspace recommendations are
enabled
- Remove setting to block individual apps from resumption
- Update strings for existing resume setting

Bug: 187925818
Test: atest SettingsProviderTest
Test: atest MediaControlsRecommendationControllerTest
Test: atest MediaControlsPreferenceControllerTest
Change-Id: I4bd6a420e01e8c44f4db8be477557501648cc8d7