Support additional basemap layers #578
Description
We currently only support two basemap layers that tend not be very accessible for users are for instance visually impaired or have not acquired map literacy yet. This excludes / makes it harder to participate for certain groups to work with the generated sketchmaps.
The heal client has implemented some potential basemaps.
https://heal.openrouteservice.org/#/place/@8.68112,49.410757,12
Maybe as well https://opentopomap.org/#map=5/49.023/10.020
Related: #363
This will not be worked on until requested by uses (more requirements have been collected)