Provide estimates of missing nutrients on products (especially fruits) using CIQUAL

[teolemon]

Problem description

In many products, the nutrition table is either missing or incomplete (eg: Selenium, Iodine,…), and some people and some apps (for nutrition tracking, or rare diseases) would want estimates.

Desired solution

Create new nutrition fields with an _estimated suffix to provide those values using average values of missing nutrients using CIQUAL

Number of products impacted

near 100%, because even for products with a legal nutrition table, we only have values for "legally printed nutrients"

[aleene]

It is also possible to use the averages of a category for this.

[github-actions]

This issue has been open 90 days with no activity. Can you give it a little love by linking it to a parent issue, adding relevant labels and projets, creating a mockup if applicable, adding code pointers from https://github.com/openfoodfacts/openfoodfacts-server/blob/main/.github/labeler.yml, giving it a priority, editing the original issue to have a more comprehensive description… Thank you very much for your contribution to 🍊 Open Food Facts