Add Volume panel

Volume panel hosts each volume stream, including:
- Media volume
- Call Volume
- Ring volume
- Alarm volume

Change-Id: I1801d10d2304c57615e9499386c638c74ffcd7c3
Screenshot: https://screenshot.googleplex.com/m764j65ECto
Bug: 117804161
Test: Manual app
Test: robolectric

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

@@ -47,8 +47,8 @@ public class InternetConnectivityPanel implements PanelContent {
     }
 
     @Override
-    public String getTitle() {
-        return (String) mContext.getText(R.string.internet_connectivity_panel_title);
+    public CharSequence getTitle() {
+        return mContext.getText(R.string.internet_connectivity_panel_title);
     }
 
     @Override