Combines def-svtv-data-export and def-svtv-data-import.
Usage:
(def-svtv-data-export/import export-name :stobj stobj-name) ;; default: sv::svtv-data
This just does def-svtv-data-export followed by def-svtv-data-import, i.e. defines a constant and 0-ary function