clean up

lib/data/services/user_service.dart

@@ -0,0 +1,11 @@
+import 'package:fcs/domain/entities/user.dart';
+
+abstract class UserService {
+  Future<void> inviteUser(String userName, String phoneNumber);
+  Future<void> deleteInvite(String phoneNumber);
+  Future<void> acceptRequest(String userID);
+  Future<User> findUser(String phoneNumber);
+  Future<List<User>> searchUser(String term);
+  Future<void> uploadMsgToken(String token);
+  Future<void> removeMsgToken(String token);
+}