ws: Use an alternate loopback SSH based login when running in container

When running in a privileged container systemd and selinux are both
very very confused if we try to run a user session from a descendant
of a daemon like docker.

So for login and starting the user session, we instead SSH into
127.0.0.1 and use that for authentication too.

Note that because we are connecting to 127.0.0.1 we can ignore host
keys.

Closes #1444