[Feature Request] Add once prop to Deferred component.

[imnash21]

Add once prop to Deferred component that means only once to show the fallback/loading, because every time I call the router.post with the only option like only: ['data'] then the loading from fallback is always popping in; it's like annoying, example you use Spinner for loading.

The scenario for my issue is about broadcasting like ProductCreated event then in frontend using the useEcho hook, the callback function I call the router.reload({ only: ['data'] });.

From backend:
'data' => Inertia::defer(...)

From frontend