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/PanelFeatureProviderImpl.java

@@ -25,6 +25,8 @@ public class PanelFeatureProviderImpl implements PanelFeatureProvider {
         switch (panelType) {
             case SettingsPanelActivity.PANEL_TYPE_WIFI:
                 return InternetConnectivityPanel.create(context);
+            case SettingsPanelActivity.PANEL_TYPE_VOLUME:
+                return VolumePanel.create(context);
         }
 
         throw new IllegalStateException("No matching panel for: "  + panelType);