[Feature Request]: Provide fallback prop to CheckoutProvider

[inlet]

What happened?

The CheckoutProvider is returning null during the prepare phase:

react-stripe-js/src/components/CheckoutProvider.tsx

Lines 208 to 210 in 885a0d7

	if (!ctx.checkoutSdk) {
	return null;
	}

Please provide a fallback component to render, example:

export function Checkout({ clientSecret }: { clientSecret: string }) {
  const stripeClient = useStripeClient();

  return (
    <CheckoutProvider
      stripe={stripeClient}
      options={{ clientSecret }}
      fallback={<div>Loading checkout...</div>}
    >
      <CheckoutForm />
    </CheckoutProvider>
  );
}

Thanks in advance!

Environment

No response

Reproduction

No response