Add navigation demo application to Flutter demo image

When the new Flutter homescreen was added, the new demo image with it did not include any other applications.  While there is SPEC-5066 to add the camera-gstreamer application to images, it makes sense to add the Qt navigation application to the new Flutter demo image to provide another example application that can be started from the "Apps" tab.  If/when the Flutter demo gets a Flutter native navigation solution, it can be removed again.