Add the visualization options to leaflet layers (low priority)

[demiangomez]

We currently have two modes of visualization: icons with warnings and just icons for the stations. It would be nice if we can add additional layers to the leaflet, as shown here, including the possibility of showing OpenTopoMap:

Besides adding the topography layer from open topo map (which is useful many times), this list must have the following options:

1. Show continuous stations (checked by default)
2. Show campaign stations (checked by default)

Additionally (i.e. in addition to showing continuous and/or campaign), if possible, we want to use two classifications

1. Classify by stations information issues:
   a) Show stations without problems (checked by default)
   b) Show stations with problems (checked by default)

2. Classify by station status: these are the station status from station meta (Active Online, Active Offline, etc)
   a) Show Active Online
   b) Show Active Offline
   c) Show Deactivated
   ....

see documentation from leaflet here:
https://leafletjs.com/examples/layers-control/