FR: Add support to API for controlling new and unknown barcodes

[pantherale0]

Thanks for this great addon for Grocy, it makes shopping much easier when I don't need to navigate loads of menus to setup an item in Grocy.

I've built an API that provides a barcode lookup service for all of the UK supermarkets (data is direct from the supermarkets themselves), I'd like to get something working with Barcode Buddy.

This is a FR to add support to the API to retrieve new and unknown barcodes and also perform related actions on them (create product etc).