LP#1942220: change how linking to Dojo interfaces is handled

LP#1942220: change how linking to Dojo interfaces is handled

This patch takes out the notion that the Angular acquisitions
interface is experimental in favor of a different setting that
controls whether or not the Angular PO summary links to the
legacy PO interface.

IOW, this change pushes the user towards using the new interfaces
and dipping into the old ones only one necessary.

Additional links (e.g., to the legacy LI worksheet page) could be
readily added as needed.

Signed-off-by: Galen Charlton <gmc@equinoxOLI.org>