Add logging for SettingsPanels

The 3 main categories are:
- Panel Opened
- Panel Closed
- Panel Slice interaction

There are 3 close events:
- See more button
- Done button
- Clicking outside the panel

Slice interactions will log the Uri of the Slice and the ActionType,
such as Toggle, Slider, Content (intent).

Change-Id: Iecad948f39f50dd12ae1bcb23a5d523e0df8bb98
Fixes: 117804231
Test: robotests

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

@@ -19,12 +19,14 @@ package com.android.settings.panel;
 import android.content.Intent;
 import android.net.Uri;
 
+import com.android.settingslib.core.instrumentation.Instrumentable;
+
 import java.util.List;
 
 /**
  * Represents the data class needed to create a Settings Panel. See {@link PanelFragment}.
  */
-public interface PanelContent {
+public interface PanelContent extends Instrumentable {
 
     /**
      * @return a string for the title of the Panel.