Update strings and layout for enterprise privacy

This CL continues the finalization of UI layout and strings for the
enterprise privacy page:
* Turn footer into a header
* Update strings
* Dynamically generate summaries for entry points in security page

Bug: 32692748
Test: m RunSettingsRoboTests

Change-Id: Ibf248ac269380fb1b919b01f88f721130060b7f9

src/com/android/settings/enterprise/DevicePolicyManagerWrapper.java

@@ -30,6 +30,13 @@ import java.util.List;
  * newer than the API version supported by Robolectric.
  */
 public interface DevicePolicyManagerWrapper {
+    /**
+     * Calls {@code DevicePolicyManager.getActiveAdminsAsUser()}.
+     *
+     * @see android.app.admin.DevicePolicyManager#getActiveAdminsAsUser
+     */
+    public @Nullable List<ComponentName> getActiveAdminsAsUser(int userId);
+
     /**
      * Calls {@code DevicePolicyManager.getMaximumFailedPasswordsForWipe()}.
      *