libcalamares: use namespace Calamares::Network consistently

src/libcalamares/geoip/GeoIPTests.cpp

src/libcalamares/geoip/Handler.cpp

src/libcalamares/network/Manager.cpp

src/libcalamares/network/Manager.h

src/libcalamares/network/Tests.cpp

src/libcalamaresui/utils/Qml.cpp

src/libcalamaresui/utils/TestPaste.cpp

src/modules/locale/Config.cpp

src/modules/netinstall/LoaderQueue.cpp

src/modules/tracking/TrackingJobs.cpp

src/modules/welcome/Tests.cpp

src/modules/welcome/checker/GeneralRequirements.cpp