Added footers to zen mode settings

ZenModeSettings Footer displays when DND will end
ZenModeBehaviorSettings Footer describes why dnd behavior cannot be changed when
in alarms only or total silence mode

Test: make RunSettingsRoboTests -j40
Bug: 63077372
Change-Id: Iefbb3995da4af2b210c8e0c3c3a798d3c613e275

src/com/android/settings/notification/ZenModeSettings.java

@@ -64,6 +64,7 @@ public class ZenModeSettings extends ZenModeSettingsBase {
         controllers.add(new ZenModeBehaviorPreferenceController(context, lifecycle));
         controllers.add(new ZenModeAutomationPreferenceController(context));
         controllers.add(new ZenModeButtonPreferenceController(context, lifecycle));
+        controllers.add(new ZenModeSettingsFooterPreferenceController(context, lifecycle));
         return controllers;
     }