New port: www/kdsoap

KD Soap is a Qt-based client-side and server-side SOAP component.

This is soon to be a dependency for KDE software, and is needed on the
KDE-FreeBSD CI already (to test the stuff that will have this as a
dependency). I'm not 100% convinced about this Makefile: the software
is released through GitHub, but a plain "USE_GITHUB=yes" doesn't
work, and can't fetch the sources. The fetch attempt goes

=> Attempting to fetch https://github.com/KDAB/KDSoap/releases/download/kdsoap-1.9.0/KDAB-KDSoap-1.9.0_GH0.tar.gz

which fails; chasing the automatic GH download links from the releases
on KDSoap's GH page leads me to

https://codeload.github.com/KDAB/KDSoap/tar.gz/kdsoap-1.9.0

while the release manager of KDSoap attaches a tarball (and GPG signature)
separately. So that's why there's a bit of "pretend" GH use and an
explicit MASTER_SITES in this port.