[Map] Leaftlet 2.0 migration

[smnandre]

Some changes to support here. We need to discuss how we can (if we can) handle both versions

https://github.com/Leaflet/Leaflet/blob/main/CHANGELOG.md

[Kocal]

Didn't even know Leaflet 2.0 was a thing!

I quickly read the breaking changes and I don't see anything preventing us to add Leaflet 2 support