Add support to map ruler based on configured projection

It would be great if we had the possibility to show a ruler around the map. This ruler should change as the projection change as well, and the frequency of the ticks should be configurable as well (eg. show the latitude every 10km and longitude every 5km if we are dealing with an UTM projection or latitude every 2º and longitude every 3º if we are dealing with geographic projection). It should be something like that:

Another example:

We already have a scale bar, which is great, but it would be very good to be able to see the ruler around the map.

No se indican archivos, pruebas ni puntos de entrada. Empieza por rastrear cómo Folium configura las proyecciones de mapas y renderiza sus mapas, y determina después cómo puede una regla seguir la proyección y exponer intervalos configurables para las marcas de latitud y longitud. Se considera terminado cuando la regla rodea el mapa, se adapta a la proyección configurada y admite intervalos configurables independientes.