Add configs to display/hide a few tiles in device info page

- Displaying/hiding Emergency info, branded account, device header
  widget are now driven by config flags
- Also refactored controllers to use BasePreferenceController

Change-Id: Ie601ebf689e0744c6a05a2cca5513fa43ef355e0
Fixes: 119607340
Test: robotests

src/com/android/settings/deviceinfo/aboutphone/TopLevelAboutDevicePreferenceController.java

@@ -35,7 +35,7 @@ public class TopLevelAboutDevicePreferenceController extends BasePreferenceContr
     @Override
     public CharSequence getSummary() {
         final DeviceNamePreferenceController deviceNamePreferenceController =
-            new DeviceNamePreferenceController(mContext);
+                new DeviceNamePreferenceController(mContext, "dummy_key");
         return deviceNamePreferenceController.getSummary();
     }
 }