Introduce a way to explore all Open Food Facts facets (a taxonomy explorer)

teolemon commented 2 years ago

[ ] Introduce a way to explore all Open Food Facts facets
- [ ] in V1, we had a category explorer + an additive explorer
[ ] Let's make it generic and create a facet explorer
[ ] It should use the Search V2 API to present faceted results, in order to avoid the limitation of 2 facets (you can only combine 2 facets at a time)
[ ] It should use the partial taxonomy API to allow navigation (or the full taxonomies if we want offline support)
[ ] Result pages should be deep-linkable with the facet syntax (eg /category/lasagne will translate to the correct Search V2 equivalent, and pages like https://world.openfoodfacts.org/labels, https://world.openfoodfacts.org/label/organic or https://world.openfoodfacts.org/label/organic/categories https://world.openfoodfacts.org/label/organic/category/beers will work - cf: #920
[ ] We can allow the user to refine a search, since it will be using the search V2 API
[ ] The code will (and should be) probably the same as Advanced search (the only differing part being the initial system to start diving into existing facets) - cf #1371
[ ] We will be able to add deep links to Hunger Games (that will allow for instance to categorize more products that may belong to this food category or food label), thus creating a virtuous circle, especially in countries where we have low completion rates (eg: https://hunger.openfoodfacts.org/questions?type=category&value_tag=en%3Abeers) - cf #2517

It can use the new Knowledge Panels for Facets API to display more info on individual values: https://github.com/openfoodfacts/openfoodfacts-dart/issues/629