TF-439 Implement get firebase subscription

lib/features/push_notification/domain/state/get_firebase_subscription_state.dart

@@ -0,0 +1,25 @@
+
+import 'package:core/presentation/state/failure.dart';
+import 'package:core/presentation/state/success.dart';
+import 'package:fcm/model/firebase_subscription.dart';
+
+class GetFirebaseSubscriptionLoading extends UIState {}
+
+class GetFirebaseSubscriptionSuccess extends UIState {
+
+  final FirebaseSubscription firebaseSubscription;
+
+  GetFirebaseSubscriptionSuccess(this.firebaseSubscription);
+
+  @override
+  List<Object> get props => [firebaseSubscription];
+}
+
+class GetFirebaseSubscriptionFailure extends FeatureFailure {
+  final dynamic exception;
+
+  GetFirebaseSubscriptionFailure(this.exception);
+
+  @override
+  List<Object> get props => [exception];
+}