Consolidate provider sources

[SylvainCorlay]

Hello, ipyleaflet developer here.

I noticed that JSON listing the provider sources is generated by _parse_leaflet_providers.py which extracts the data from https://github.com/leaflet-extras/leaflet-providers with Selenium. This seems a bit overkill. Did anyone try reaching out to the developers of leaflet-providers so that this information is directly available in a standalone JSON file?

This JSON file could also directly be packaged independently of the rest of the JS logic of leaflet-providers.

cc @HaudinFlorence.

[martinfleis]

Hey, I don't think so. When we created xyzservices the code scraping the data from leaflet-extras/leaflet-providers was already existing in contextily and we just moved it here. But I agree that it may be worth checking with them if it could be simplified.

[SylvainCorlay]

I opened an issue about this upstream: leaflet-extras/leaflet-providers#457.