add qgis

[jrmarino]

https://cgit.freebsd.org/ports/tree/graphics/qgis

This replaces the remove of the gui of postgis seen in issue #314

[jrmarino]

We need to wait for qgis 4.0 for full QT6 support. right now everyone is building with qt5 even though 3.44.7 seems to have removed qt6 options (implying it's required not optional). Not sure what's going on.

[jrmarino]

release 4.0 due on 20 Feb.