[custom map suggestion] Add the ability to use arbitrary mapbox styles as custom layers

[pfbreton-perso]

I noticed that Mapbox styles are used for some of the layers now. I developed my own Mapbox styles and by hacking around I managed to override locally one of the map style which demonstrated that by passing around the correct URL it works here is an image showing my local hack where I redirected the Mapbox Outdoors styl to my own.

Since we can alreay create our own layers which uses a WMTS protocol (XYZ tiles) it seems that we could also allow for custom mapboxstyles & tokenns.