Use database IDs instead of product names to locate products and associate them with related products

Relying on product names while searching for them (including `relatedProductsNames` field) is error-prone, because a product data can be modified when it's name is changed. Setting `name` field as unique might be a workaround solution, but the `name` field should be able to be changed at least for a reason of doing a typo while creating a product.