Function is_advisory_only_code 

pub fn is_advisory_only_code(code: &str) -> bool

Whether a rendered diagnostic code string (e.g. "E1004") is advisory-only.

The string-keyed counterpart to ErrorCode::is_advisory_only, for consumers (the CLI check/lint split) that only carry the code string. Keeping it here means the set of advisory-only codes lives in one place.