Show custom label format only for cursor position in plot

Hey everyone,

I'm planning to show the unit of each axis in the name of the axis. It seems a bit excessive to show the unit on every tickmark, However I do want to show the unit in the cursor position (bottom right of every plot when the cursor is over it).

For now it seems that there's no option to do this. You can either have labels everywhere, or nowhere.

Green = wanted, red = unwanted.

I haven't figured out where exactly this is done in the code but maybe it would be helpfull to create a `ImPlotFlag_NoCustomLabelOnTicks`.

Is anyone willing to help me out on where to begin for adding this? I'm not very experienced with making pull requests yet.