Add dynamic group panel

-Rename PanelCustomizedButtonCallback to PanelContentCallback
-Add onGroupChanged in PanelContentCallback
-Add test cases

Bug: 146813761
Test: make -j42 RunSettingsRoboTests
Change-Id: I60888efbbd0fc2878467418e55c70887a9d3f405

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

@@ -100,5 +100,5 @@ public interface PanelContent extends Instrumentable {
      *
      * @param callback the callback to add.
      */
-    default void registerCallback(PanelCustomizedButtonCallback callback) {}
+    default void registerCallback(PanelContentCallback callback) {}
 }