Add switch for KF5 (QT6) and Mod Cmake

if we want to test QET on QT6, KF5 must be removed from the code,
this switch is for that,

this is for testing only

sources/qetproject.h

@@ -27,8 +27,10 @@
 #include "properties/xrefproperties.h"
 #include "titleblock/templatescollection.h"
 #include "titleblockproperties.h"
-
-#include <KAutoSaveFile>
+#ifdef BUILD_WITHOUT_KF5
+#else
+#	include <KAutoSaveFile>
+#endif
 #include <QHash>
 
 class Diagram;
@@ -40,7 +42,10 @@ class NumerotationContext;
 class QUndoStack;
 class XmlElementCollection;
 class QTimer;
+#ifdef BUILD_WITHOUT_KF5
+#else
 class KAutoSaveFile;
+#endif
 
 /**
 	This class represents a QET project. Typically saved as a .qet file, it
@@ -68,7 +73,10 @@ class QETProject : public QObject
 	public:
 		QETProject (QObject *parent = nullptr);
 		QETProject (const QString &path, QObject * = nullptr);
+#ifdef BUILD_WITHOUT_KF5
+#else
 		QETProject (KAutoSaveFile *backup, QObject *parent=nullptr);
+#endif
 		~QETProject() override;
 
 	private:
@@ -267,7 +275,10 @@ class QETProject : public QObject
 		bool m_freeze_new_conductors = false;
 		QTimer m_save_backup_timer,
 			   m_autosave_timer;
+#ifdef BUILD_WITHOUT_KF5
+#else
 		KAutoSaveFile m_backup_file;
+#endif
 		QUuid m_uuid = QUuid::createUuid();
 		projectDataBase m_data_base;
 };