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.

未指定文件、测试或入口点。首先跟踪 Folium 如何配置地图投影并渲染其地图，然后确定标尺如何遵循投影，并提供可配置的纬度和经度刻度间隔。完成的标准是标尺环绕地图、适应已配置的投影，并支持分别配置间隔。