refactor: MVC sign up password view

test/sign_up_password_test.dart

@@ -0,0 +1,16 @@
+import 'package:fluffychat/controllers/sign_up_password_controller.dart';
+import 'package:fluffychat/main.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  testWidgets('Test if the widget can be created', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      FluffyChatApp(
+        testWidget: SignUpPassword(
+          'test_user',
+          displayname: 'Test User',
+        ),
+      ),
+    );
+  });
+}