Add captureMethod to Stripe Elements options

- Update payment_element_options hash to include the `captureMethod` parameter
- Ensure captureMethod value matches the capture_method provided when creating
the Payment Intent

Adding `captureMethod` improves security by ensuring that the capture_method
value used during payment method creation matches the value provided when
creating the Payment Intent. This helps prevent fraudulent activity and errors,
such as a scenario where an admin changes the auto-capture mode during the
confirm to complete order transition, causing the payment to fail.

Reference: https://stripe.com/docs/js/elements_object/create_without_intent

lib/generators/solidus_stripe/install/templates/app/views/checkouts/payment/_stripe.html.erb

@@ -6,6 +6,7 @@
   ),
   currency: current_order.currency.downcase,
   paymentMethodCreation: 'manual',
+  captureMethod: payment_method.auto_capture? ? 'automatic' : 'manual',
   # Fully customizable with appearance API.
   # https://stripe.com/docs/elements/appearance-api
   # appearance: {},