Box2D & Box3D aren't json serializable

[ahawlitschek]

Since Geojson has no geometry type for box, we had not implemented the interface providing the necessary code to serialize it.
@saibotk I would suggest we add a custom serialization besides the JsonGenerator that returns all 4 floats as array (as accepted by most of the frontend map libraries)

[saibotk]

Sounds good,

But we may also want to look into https://datatracker.ietf.org/doc/html/rfc7946#section-5
and see if there are any available usecases for also supporting bbox properties on GeoJson in Magellan.