Correct instantiation of attribution control

[erictheise]

Working on attribution strings downstream at OHM it appears that these two lines have no effect. An attribution control needs to be instantiated, then added to the map like this

const attribControl = new L.Control.Attribution({position: "bottomright"});
attribControl.addAttribution(tilesAttrib);
attribControl.addTo(ide.map);

Note that the attribution control that appears on the live site is the one created when the Leaflet map is initialized, as {prefix: false} is not honored.

[tyrasd]

should be fixed with #703, right?