Add support for the Folksonomy Engine in the mobile app (Tracker issue)

[teolemon]

What

### Tasks
- [ ] Define and agree on an input/editing UI
- [ ] Define and agree on a display UI (and grasp how we articulate that with the new product page, without polluting it)
- [ ] The login mechanism will be in common with the main API
- [ ] Add UI support for logging in to Folksonomy engine and the main Open Food Facts backend.
- [ ] https://github.com/openfoodfacts/smooth-app/issues/5218
- [ ] https://github.com/openfoodfacts/smooth-app/issues/5219
- [ ] https://github.com/openfoodfacts/smooth-app/issues/5861
- [ ] https://github.com/openfoodfacts/smooth-app/issues/5854

Blocked on

• https://github.com/openfoodfacts/openfoodfacts-dart/issues/158

Why

• This will enable us to collect targeted data on food products without having to evolve the OFF core data model
  • eg: the weight of packaging elements
• This will enable us to model non-food products on Open Product Facts
• This will enable us to trigger custom behaviors in the app (eg for recalled products, and potentially public/private lists of products)

Mockups

Part of

• 525

• https://github.com/orgs/openfoodfacts/projects/5/views/1

[teolemon]

Bumping priority, since it's going to be a part of Open Products Facts