Function start_loop 

pub fn start_loop(
    state: Arc<PresenceDnd>,
    own_name: String,
    on_change: impl Fn(PresenceState) + Send + 'static,
)

Start the polling loop. It samples only while a preference needs it, never calls into the app thread, and ends when the process does. on_change receives the new state when an automatic flag flips.