Update GeoJSON

In Mapdeck, to use a value from a geojson property as a colour it needs to be converted to sf first, then run through spatialwidget, then back to geojson. This incurs a performance cost

It would be better if the GeoJSON could be manipulated directly.

A possible solution is to iterate through each property value the user asks for, create a vector of data, colour it, update the original geojson with the colour, continue, plot, win.