Show loading page for PENDING payment

[jimmyn]

If the customer is redirected to the complete URL but the payment status is PENDING (which can occur in various scenarios, such as with MBWay), we should direct the customer to the loading page and wait for the callback. However, in the case of Multibanco, we should not redirect the user since the callback can take up to seven days.

Check https://github.com/MONEI/MONEI-AdobeCommerce-Magento2/blob/main/Controller/Payment/Complete.php#L329