the host query parameter can now be used
dependent on the `hostselection` config.

Cobra is pretty opnionated and its complexity isnt required
currently.

AD and other IdPs can provide long lists of group
membership. This can lead to securecookie too big
as this cannot always be stored inside a HTTP header.
Filesystem session storage removes this limitions at the
cost of not being entirely stateless anymore. It is therefore
required that clients can keep state with the rdpgw
instance.