DND ixD changes

- Subtext in Settings > Sound updated
- new icons for automatic dnd rules
- no toast when toggling on/off dnd rules
- dnd dialog has a warning if dnd will cause user to miss next alarm

Test: make ROBOTEST_FILTER=ZenModePreferenceControllerTest RunSettingsRoboTests -j40
Fixes: 72494029
Fixes: 72655216
Fixes: 72655609
Change-Id: I9d86d82529079f35e362f93e10914f0a60229cd8