Add onUpdate() configuration to service worker registration

Created by: richarddd

This enables users to tell the service worker to skip waiting.

Example:

serviceWorker.register({
  ...
   onWaiting((waitingWorker) => {
     waitingWorker.postMessage({ type: "SKIP_WAITING" })
     window.location.reload();
   })
...
});

This PR also adds check if multiple service workers are registered so only the correct one triggers the callbacks we pass to serviceWorker.register