Add Stripe checkout partial

[duncanmcclean]

<div class="border rounded p-2 mb-2 text-gray-600 focus:text-gray-800 outline-none" id="card-element"></div>
<input id="stripePaymentMethod" type="hidden" name="payment_method">

<script src="https://js.stripe.com/v3/"></script>
<script>
    var stripe = Stripe('{{ gateway-config:key }}');
    var elements = stripe.elements();

    const card = elements.create('card');
    card.mount('#card-element');

    card.addEventListener('change', ({error}) => {
        const displayError = document.getElementById('card-errors');

        if (error) {
            alert('There was an issue when loading: '+error.message);
        }
    });

    function confirmPayment() {
        stripe.confirmCardPayment('{{ client_secret }}', {
            payment_method: {
                card: card,
            },
        }).then(function (result) {
            if (result.error) {
                alert(result.error.message);
            } else if (result.paymentIntent.status === 'succeeded') {
                var paymentMethod = document.getElementById('stripePaymentMethod');
                paymentMethod.value = result.paymentIntent.payment_method;
                document.querySelector('form').submit();
            }
        });
    }
</script>