Function format_candidate_status 

pub fn format_candidate_status(
    name: &str,
    namespace: &str,
    candidate: &Value,
    plan_name: Option<&str>,
    plan: Option<&Value>,
) -> String

Render pgroles candidate status for one candidate and its plan.

plan is None when the candidate has not been planned yet — the caller reports that as a hard error for diff, but status is exactly the command that should be able to explain an unplanned candidate.