Improve multi user functionality for restricted users

- Restricted users can change their name
- Improved App&Content access screen
- Remove "Turn on phone calls" from restricted user detail page

Doc: http://shortn/_Prb3SJ3xJ3
Bug: 142798722
Test: Run robo tests with this command:
  make -j64 RunSettingsRoboTests
Change-Id: I2aadf32aef52ba5ad0db7aa0cd83bac9d9941589

src/com/android/settings/Utils.java

@@ -116,6 +116,8 @@ public final class Utils extends com.android.settingslib.Utils {
 
     private static final String TAG = "Settings";
 
+    public static final String FILE_PROVIDER_AUTHORITY = "com.android.settings.files";
+
     /**
      * Set the preference's title to the matching activity's label.
      */