API November 2024 improvements

• Added - added get-product-variants endpoint with pagination and the ability to filter by barcodes
• Improved - add retailer_basket_code to referral relation and use in redemption tracking
• Improved - added reward redemption count and progress to get-campaigns output for end users
• Improved - allow editable campaign assignment groups
• Improved - allow supplier contribution in a basket campaign to be set to null
• Improved - check whether assigned_groups parameter for campaign is an array
• Improved - database improvements in communications with Magento 2 REST API and module
• Improved - extended product endpoints to allow product, product variant and barcode deletion
• Fixed - fixed issue with max_reward_quantity when successive baskets do not contain complete reward complement
• Fixed - fixed rounding issue when meal deal and free basket competition are used at the same time