[Feature Request] Request Online Payment vendor

[siniztr]

This is a request to add the Online Payment vendor Mollie. This is a very popular European payment vendor. The documentation for doing so can be found here: https://docs.mollie.com/
By adding this payment vendor, it opens users up to accepting many types of payments, such as bank transfers, paypal, apple and and google pay, as well as many EU countries instant bank transfers (Dutch: iDeal, Belgium:BanContact, etc.)

[nielsdrost7]

Todo:
https://github.com/thephpleague/omnipay-mollie :
composer require league/omnipay omnipay/mollie
Then use basic purchase example from the readme (if needed)
Then edit application/config/payment_gateways.php

The payment goes through https://github.com/InvoicePlane/InvoicePlane/application/modules/guest/controllers/Payment_handler.php
The setting is: https://github.com/InvoicePlane/InvoicePlane/application/modules/settings/views/partial_settings_online_payment.php