chore(mobile): refactor authentication (#14322)

mobile/lib/interfaces/auth_api.interface.dart

@@ -0,0 +1,9 @@
+import 'package:immich_mobile/models/auth/login_response.model.dart';
+
+abstract interface class IAuthApiRepository {
+  Future<LoginResponse> login(String email, String password);
+
+  Future<void> logout();
+
+  Future<void> changePassword(String newPassword);
+}