Add "Scale Legend Change" as an event for graphs

[nanocyte]

I want an event to trigger when the user switches from linear to logarithmic mapping for a control. 

None of these currently existing events trigger for this scale change

Related forum discussions:

https://forums.ni.com/t5/LabVIEW/Can-I-detect-a-plot-name-change-event-in-a-plot-legend/td-p/2741164

https://forums.ni.com/t5/LabVIEW/XY-Plot-Scale-Legend-Mapping-Mode-Changed-Event/m-p/4226689