[Fast-track] Adding a photo with another language is not recognized as "added"

[g123k]

Hi everyone,

When we have what we call the "Fast-track" screen (= non-existing product), we first ask for photos.
However, if a photo is taken in a language different from the default one, we never have the green mark

In the video of #5226, we can see the issue at 00:25
https://github.com/openfoodfacts/smooth-app/assets/246838/05ce073d-4ed5-40ae-88e6-45b894c86891

[g123k]

Today, the button turns green when a photo with the correct type/(default) language is available.
The problem is when the photo was taken in a different language.

Here are a few possible fixes:

• The photo screen returns a Boolean to indicate whether a photo has been added/edited.
• The photo screen returns a List of languages added/modified.
  -> Option 1: In both cases, if the result is not empty, we can assume it's OK

But the photo may still be sent in the background.
Option2: Should we then go with a List of languages AND do the same check as today… but with the correct language

(cc @monsieurtanuki @teolemon)

[monsieurtanuki]

@g123k Actually we don't care if the background task hasn't been completed yet: we override the product with the pending data.

Quickly said: I would have a look at BackgroundTaskUpload, method getProductChange and

  @override
  Future<void> preExecute(final LocalDatabase localDatabase) async {
    await localDatabase.upToDate.addChange(
      uniqueId,
      getProductChange(),
    );
    await putTransientImage(localDatabase);
  }

Including UpToDateChanges._overwrite too, the way it deals with images.

Then, I guess looping the product images looking for at least one "nutrition" picture would be enough.