Extract Category Finder for Ingredients to separate API

[wp99cp]

The export function uses an algorithm to find a food category of a given ingredient name, e.g. "Peperoni" gets categorized as "Früchte & Gemüse". This algorithm gets quite complicated, as it should work reliable also for combined or misspelt words, e.g. "Walliserbrot" should be classified as "Backwaren" even if the algorithm only knows "Brot" and not "Walliserbrot".

As spelling correction and classification could also be of interest for the frontend or other backend services (e.g. for classifying recipes), we should encapsulate these steps away from the export of the camp, by creating a separate API.