CMake: Enable type forcing for CMake configuation values

Allow to force the type for CMake configuration values, now that
this type changes how you can edit the values.

Change-Id: Id89e0ec8547b778fc0aff9a2e00c0d7406cbcac1
Reviewed-by: hjk <hjk@qt.io>

src/plugins/cmakeprojectmanager/cmakebuildsettingswidget.h

@@ -65,6 +65,7 @@ private:
     void updateFromKit();
 
     void updateSelection(const QModelIndex &current, const QModelIndex &previous);
+    QAction *createForceAction(int type, const QModelIndex &idx);
 
     bool eventFilter(QObject *target, QEvent *event);