cli: add SHELL environment variable to "rad debug" output — heartwood

Signed-off-by: Lars Wirzenius liw@liw.fi

     let env = HashMap::from_iter(env::vars().filter_map(|(k, v)| {
         if k == "RAD_PASSPHRASE" {
             Some((k, "<REDACTED>".into()))
         } else if k.starts_with("RAD_") || k.starts_with("SSH_") || k == "PATH" {
         } else if k.starts_with("RAD_") || k.starts_with("SSH_") || k == "PATH" || k == "SHELL" {
             Some((k, v))
         } else {
             None