Eco-score from BarCodeScanner

[PierreBresson]

Some work has already been done in #300, here is what needs to be done :

• [x] #316
• [x] #317
• [x] #319
• [x] #320

Use api of open food fact to get eco-score from product barcode and add thie eco-score as an emission in the app. See :

• https://docs.expo.io/versions/latest/sdk/bar-code-scanner/
• https://wiki.openfoodfacts.org/API#READ_operations
• https://github.com/openfoodfacts/openfoodfacts-react-native