toggle create-geojson icon on closing of right sidebar with x

Just adding back the `closeButton: true` so we can close the sidebar using Leaflet's built-in 'x' - the previous issue dealt with the `create-geojson` icon not toggling back to 'inactive' but now there's just a quick jQuery check to push it back to its normal state.

**Note:** this is *only* for the right sidebar right now, would be good to check for any sidebar that's opened in the future.