Function encode_userinfo_with_scheme 

fn encode_userinfo_with_scheme(
    scheme: &str,
    addr: SocketAddr,
    username: &str,
    password: Option<&str>,
) -> Option<(String, Option<String>)>

URL-encodes username and optional password for a given scheme and address.

Builds a URL from scheme://addr, sets username/password, and returns the percent-encoded forms suitable for URI userinfo display.