Expose biometric availability

Author: Guldem

lib/pin_lock.dart

@@ -11,6 +11,7 @@ import 'package:pin_lock/src/repositories/pin_repository_impl.dart';
 import 'package:shared_preferences/shared_preferences.dart';
 
 export 'package:pin_lock/src/entities/authenticator.dart';
+export 'package:pin_lock/src/entities/biometric_availability.dart' show Available, Unavailable;
 export 'package:pin_lock/src/entities/biometric_method.dart';
 export 'package:pin_lock/src/entities/failure.dart';
 export 'package:pin_lock/src/entities/lock_controller.dart';