pub fn new_sibling<T2>(&self) -> (watch::Sender<Option<T2>>, CookiedOptionalWatch<T2, U>) {
        let (tx, rx) = watch::channel(None);
        (
            tx,
            CookiedOptionalWatch {
                value: rx,
                cookie_index: self.cookie_index.clone(),
                cookie_writer: self.cookie_writer.clone(),
                parent: self.parent.clone(),
            },
        )
    }
Create a new sibling cookie watcher that inherits the same fs source as
this one.
crates/turborepo-filewatch/src/cookies.rs