Import CityGML/CityJSON files

Add the possibility to directly import 3D models conform the CityGML data standard (https://www.ogc.org/standards/citygml), such as CityGML files and CityJSON files.
This will make it easier to import detailed 3D models and architectural designs into the Tygron Platform, including textures.

Documentation:

https://support.tygron.com/wiki/CityGML

https://support.tygron.com/wiki/How_to_import_a_CityGML/CityJSON_file