pub(crate) async fn ensure(broker: &Broker, name: &str) -> Result<(), String>Expand description
What connensure does: accept local; accept a WSL distro that is
installed (Windows only), which is then connected; accept an SSH
destination where the system ssh is, claiming nothing (only a login
connects it: a pane’s ssh, or connconnect); refuse a bad name with the
reason, recorded as the status the pane’s overlay shows.