add pin login and add pin code

lib/data/services/auth_service.dart

@@ -15,4 +15,10 @@ abstract class AuthService {
   Stream<User?> getUserStream();
   Stream<Setting> getSetting();
   Future<void> deleteAccount();
+  Future<void> pinLogin(
+      {required String currentUserId,
+      required String fcsID,
+      required String pin});
+  User? getPinLoginUser();
+  Future<void> logoutPinAccount();
 }