feat: Add the name of the image contributor

[g123k]

Hi everyone,

On the images field, the API returns the contributor's name.
Eg:

        "images": {
            "1": {
                "sizes": {
                    "100": {
                        "h": 71,
                        "w": 100
                    },
                    "400": {
                        "h": 284,
                        "w": 400
                    },
                    "full": {
                        "h": 1089,
                        "w": 1536
                    }
                },
                "uploaded_t": 1345799270,
                "uploader": "openfoodfacts-contributors"

[monsieurtanuki]

_ALL_IMAGES_TAG_UPLOADED appears in both allImagesToJson and allImagesFromJson.
In your code _ALL_IMAGES_TAG_UPLOADER appears only once. Probably something needs to be fixed.
Additional unit tests would help, too.

[g123k]

I didn't include the 'to' method on purpose, because today, images are well assigned to the contributor.
But I can add do, no pb.

In terms of tests, despite checking the result of the server, I don't really see any benefits here.

[teolemon]

Thanks @g123k @M123-dev
Just to be sure, are we getting it as part of the standard payload ? Are there some cases where it might not be desirable (eg coke with loads of images ?)