net/ntopng: Fix GeoIP data download script

MaxMind now requires a free account with an API key to access its
APIs to download the GeoLite2 datanases.

Update scripts to adapt to new API interface and use API key provided
via %%LOCALBASE%%/etc/GeoIP.conf

Update pkg-message to provide this information.

Reported by: thedoctorjtd <76110609+thedoctorjtd@users.noreply.github.com>
Obtained from: https://github.com/freebsd/freebsd-ports/pull/182