Function spawn_metrics_collector 

pub fn spawn_metrics_collector<S, C, M>(
    store: Arc<Mutex<S>>,
    docker: C,
    metrics_collector: M,
    config: CollectorConfig,
    shutdown: Receiver<bool>,
) -> JoinHandle<()>
where
    S: TelemetryStore + Send + 'static,
    C: DockerClient + Send + Sync + 'static,
    M: MetricsCollector + Send + Sync + 'static,

Spawn a background metrics collector that periodically writes to the store.

Returns a watch::Receiver<CollectionStats> that can be polled for progress and a JoinHandle to the background task.