Set QML debugging automatically off if no QML is used within the project.

Following request came from a user:

"I notice that when I create a regular QWidgets project and compile and run I get the message : "QML debugging is enabled. Only use this in a safe environment."

This is because in the project settings qml debugging is checked even though my project does not use qml.

since the qtcreator can detect the use of qml (CONFIG or the use of qml files), it would make sense to enable ONLY if qml is used."