Update credit card payment method payload in Payments Apps API 2023-07 release

As of 2023-07 Payments Apps API version for credit card payments app extensions, we're changing the structure of the decrypted message of payment_method.data.encrypted_message sent in the HTTP request body from Shopify to your payments app. This change aims to consolidate the API design that we follow, as demonstrated in the payment_method object.

Learn more about the decryption of the encrypted_message on Shopify.dev.