[C++] Rename Qt5 to Qt (#9490)

* rename qt5 to qt

* rename, update

* rename qt5 to qt in the templates

* update doc

samples/client/petstore/cpp-qt/PetStore/PetApiTests.h

@@ -0,0 +1,17 @@
+#pragma once
+
+#include "../client/PFXPetApi.h"
+
+using namespace test_namespace;
+
+class PetApiTests : public QObject {
+    Q_OBJECT
+
+    PFXPet createRandomPet();
+
+private slots:
+    void findPetsByStatusTest();
+    void createAndGetPetTest();
+    void updatePetTest();
+    void updatePetWithFormTest();
+};