Add filtering to notification channel settings

Allow apps that are launching this page to specify targeted subsets of
settings that should be shown.

Test: settings notification robotests
Bug: 177246841
Change-Id: Ib491c43f1861a9775e3b25f39134cdbe105a7ff8

src/com/android/settings/notification/app/ConversationNotificationSettings.java

@@ -49,7 +49,7 @@ public class ConversationNotificationSettings extends NotificationSettings {
 
         for (NotificationPreferenceController controller : mControllers) {
             controller.onResume(mAppRow, mChannel, mChannelGroup, mConversationDrawable,
-                    mConversationInfo, mSuspendedAppsAdmin);
+                    mConversationInfo, mSuspendedAppsAdmin, null);
             controller.displayPreference(getPreferenceScreen());
         }
         updatePreferenceStates();