Function extract_request_bearer_token 

pub fn extract_request_bearer_token<B>(
    request: &Request<B>,
) -> Result<Option<&str>, Error>

Extract raw Bearer credentials from a complete request.

This reads request.headers() and delegates to extract_header_bearer_token, preserving its missing, scheme-mismatch, empty-credential, and field-error behavior. No token validation or authentication is performed.