Added payment service integration for reminders

In the Reminder and Issued Reminders, it is now possible to choose a payment service provider like Mollie or MultiSafepay. This payment service will be automatically transferred to the issued reminder once a reminder is issued.

Below is the new field in the Reminder:

Below is the new field in the Issued Reminder:

Then, once the Reminder report is printed, the layout will contain the QR Code and link for the payment service: