fix(phpstan): update variable types and fix bug conditions

This commit brings a number of changes across multiple files. The changes include adjustment of
variable types, fixing conditions, and the optimization of method calls.

1. In src/QUI/ERP/Order/AbstractOrderProcessProvider.php, the function getDisplay has had its
parameters realigned with AbstractOrderingStep, providing a clear type definition.

2. src/QUI/ERP/Order/EventHandling.php has changed the onDetailEquipmentButtons function to expect
a ProductTypeInterface, enabling a wider range of object types to be passed in.

3. src/QUI/ERP/Order/Factory.php now only checks for an empty orderId, rather than also improperly
comparing to zero.

4. src/QUI/ERP/Order/FrontendUsers/Controls/UserOrders.php, a fallback has been added for when the
method getImage does not exist on a Product object.

5. src/QUI/ERP/Order/Mail.php has been updated to use the correct customer address method based on
the user's type.

6. Lastly, in src/QUI/ERP/Order/OrderView.php, the getShippingStatus method now correctly specifies
null as a possible return type.

Related: #172