OBPIH-6969 Improve approach to product creation and stock data

[alannadolny]

The main idea of this improvement is to simplify adding new products and inventories. Current solution doesn't require adding new data in env, app config, etc. To create a new product or inventory, it is needed to fulfill the CSV that can be found in src/setup/dataImport. The data is loaded on every setup before running tests. If there will be a need to remove inventories or import other products while running specific tests, it is needed to create a new CSV file (for inventories with 0 qty, if removing) and call the endpoint that is called during setup. ID of every product that was created can be found in .data.json, so it's accessible by product code using helper methods that were created previously. Product data is also accessible from the AppConfig, but to get the specific that, there is a need to pass the product code. At this moment, productService is exactly the same service for every product. To change the product on which all of the operations will be executed, you should call setProduct and pass the product code.

[awalkowiak]

I think it looks ok, maybe I would think next how to improve these lines:|

productService.setProduct('1');
const PRODUCT_ONE = await productService.getProduct();
productService.setProduct('2');
const PRODUCT_TWO = await productService.getProduct();

to just have a list or something, but for now we could go with what you have.