Return the spatiotemporal bounding box expanded in the spatial dimension by a float value

expandSpace({geo,tpoint},float) → stbox

SELECT expandSpace(geography 'Linestring(0 0,1 1)', 2);
-- SRID=4326;GEODSTBOX X((-2,-2),(3,3))
SELECT expandSpace(tgeompoint 'Point(0 0)@2001-01-01', 2);
-- STBOX XT((-2,-2),(2,2),[2001-01-01,2001-01-01])