Implements tests for basket attribute client in catalog detail view
Removes unused code in basket client of catalog detail view
Minor improvements when inserting product list test data
Implements selection client in catalog detail view for product variants
Additionally, fixes a problem in the basket controller with incomplete and non-unique variant attributes when checking selection products
Adapts the unit test data and the dependent tests in the catalog index manager tests
Extends ProductPrice plugin to handle selection products correctly
Important: The order product ID is now the ID of the parent product of a selection while the product code is still the code of the article