The watchdog was used in a few places as a shortcut to skip reading
data. Further, it was used in some places in the UI to display
connectivity. But it also introduced quite some complexity. In some
cases it can be fragile: network accessibilty cannot be looked up on all
platforms/hardware constellations. The connectivity could change
between the last watchdog call and the real call. Hence all readers must
still handle the case where the connection fails.
To simplify swift and further reduce the dependency onto the project
infrastructure (pings etc.), this removes the watchdog.
This also removes the QNetworkConfigurationManager, which is deprecated
and not available with Qt6.
