Extended the method existence checks throughout src/QUI/ERP/Order/Basket/ files. Improved the
robustness of the code by ensuring that methods such as 'getUuid', 'getProductSetParentUuid',
'getQuantity', 'toArticle', and 'getAttributesForUniqueField' exist before calling them, thus
preventing potential undefined method errors. Removed unnecessary comments used for type hinting in
favor of functional checks.

Related: #172

This commit fixes several areas:

1. It changes class type in BasketOrder from QUI\\Users\\User to QUI\\Interfaces\\Users\\User.

2. It refactors Order to better handle if statements and moves verification of class existence up
to the beginning. Fix involves assuming that function getInvoiceAddress and getDeliveryAddress
always return a non-null value. It also updates on how we check class exists for Shipping data.

3. In OrderInProcess, now we check if method 'toArticle' exists on the Product object before
calling it and applies similar class checking like in Order for Shipping data.

4. Corrects and standardizes the casing for exception catching in OrderProcess.

In summary, these changes lead to a safer and cleaner code base by addressing potential Null
Pointer Exceptions and ensuring the existence of classes before they are being called.

Related: #172

Improve readability and interpretability of code by explicitly stating null in union types. This
change has been applied across multiple files and functions.

PHP8.4 compatibility

refactor: merge product list method -> Takes a product array and brings together all products that can be brought together

refactor: order process -> new event onOrderProcess; next step -> scroll to top; empty article no considered; shopping card type events