Function encode_userinfo 

fn encode_userinfo(
    version: SocksVersion,
    addr: SocketAddr,
    username: &str,
    password: Option<&str>,
) -> Option<(String, Option<String>)>

URL-encodes username and optional password for SOCKS proxy userinfo display.

Uses Url parsing to produce percent-encoded forms suitable for socks://user:pass@host:port style output.