WIP - Add system notifications for document upload progress/status

lib/features/notifications/cubit/notification_state.dart

@@ -0,0 +1,16 @@
+part of 'notification_cubit.dart';
+
+abstract class NotificationState extends Equatable {
+  const NotificationState();
+
+  @override
+  List<Object> get props => [];
+}
+
+class NotificationInitialState extends NotificationState {}
+
+class NotificationOpenDocumentDetailsPageState extends NotificationState {
+  final int documentId;
+
+  const NotificationOpenDocumentDetailsPageState(this.documentId);
+}