CPL_DEBUG statements for GUI #714
Description
The Qt4 GUI included CPL_DEBUG statements for GUI actions. We should replicate and expand these message for the Qt6 GUI.
Since the GUI and ninja code are interacting via the API, we should tag the GUI debug statements differently from the ninja debug statements. For example, the Qt4 GUI would tag all debug statements as STATION_FETCH for fetching relating to Point Initialization. Our Qt6 tags should show some differentiation, like GUI_POINT.