Get an instance of AuthenticationView. It will try to load a class that
is defined in the system property
com.gluonhq.charm.connect.view.AuthenticationView
. If no such property
was defined, it will try to load the Glisten implementation of the
AuthenticationView. When that fails to instantiate as well,
null
will be returned, which means no authentication can be
started in this application.
Note: only one instance of the AuthenticationView will be created for the entire
application. This means that subsequent calls to this method will always return
the same instance.