Support updated rendering of conversation icons.

Note that changes to channel settings now generate
onResume() for all available controllers to ensure they get
the updated drawable.

Bug: 149747760
Change-Id: I3f73c025b1d32194e3d5147d03cb781e370f2a1b
Test: make -j64 RunSettingsRoboTests ROBOTEST_FILTER="com.android.settings.notification"

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

@@ -86,6 +86,7 @@ public class ConversationHeaderPreferenceController extends NotificationPreferen
                     .setHasAppInfoLink(true)
                     .setRecyclerView(mFragment.getListView(), mFragment.getSettingsLifecycle())
                     .done(activity, mContext);
+
             pref.findViewById(R.id.entity_header).setVisibility(View.VISIBLE);
         }
     }