A coercion function for extracting a 'bbox' object that can usualy be obtained by sf::st_bbox(). This coercion
function was created to easily extract the boúnding box from the openeos argument objects BoundingBox() and GeoJson().
`as.bbox.bounding-box`(from)
as.bbox.geojson(from)a BoundingBox() argument object or a GeoJson() argument object
a bbox object from sf::st_bbox()