Output switcher header is not updated with the latest media content

-Register media controller callback
-Update panel header when medadata changes
-Add test cases

Bug: 151396986
Test: make -j50 RunSettingsRoboTests
Change-Id: Id0b8f997899a96c0c94ca6bf099e624a9e87795b

src/com/android/settings/panel/PanelFragment.java

@@ -426,8 +426,10 @@ public class PanelFragment extends Fragment {
         }
 
         @Override
-        public void onGroupChanged() {
+        public void onHeaderChanged() {
             ThreadUtils.postOnMainThread(() -> {
+                mTitleIcon.setImageIcon(mPanel.getIcon().toIcon(getContext()));
+                mHeaderTitle.setText(mPanel.getTitle());
                 mHeaderSubtitle.setText(mPanel.getSubTitle());
             });
         }