Add support for showing producer provided and protected fields

[teolemon]

Problem

• Add support for showing producer provided and protected fields
• A new version of the OFF website has been deployed. It contains in particular a change to the product edit form, to highlight which values have been provided by the manufacturer. Those values can be changed only by moderators, but previously it was not indicated and that caused users to waste time and efforts trying to change things that could not be changed. e.g. reported on the forum: https://forum.openfoodfacts.org/t/some-products-cannot-be-modified-vendor-lock/594
• It's this field https://fr.openfoodfacts.org/produit/3017620425035/nutella-ferrero.com?fields=owner_fields
• On the other hand it contains tag type fields, they must be ignored because the value could have changed afterwards and it is not protected

Mockups

Part of

• Contribute (Tracker) #503

[VaiTon]

Related forum post: https://forum.openfoodfacts.org/t/auchan-tourteau-fromage-invalid-serving-size/613/4

[M123-dev]

Waiting for: openfoodfacts/openfoodfacts-dart#956

[monsieurtanuki]

I don't know how we are supposed to display the "owner fields".

current display	display with "owner locked" fields

[teolemon]

• something we've never done is a replicate the product edit history you have at the bottom of the product page in the web version.
• in the web the product owner is displayed in a warning tooltip (some of the database product has been provided by the producer blah)
• I would believe that all of this should be less prominent than on the web version and possibly at the bottom of the page or in a special tab if we follow the proof of concept design.

[monsieurtanuki]

something we've never done is a replicate the product edit history you have at the bottom of the product page in the web version.

That would definitely deserve a separate issue. Plus a lot of additional code in off-dart (specifically for "product image for version x"). That would be for hard-core users, that have an interest in previous versions.

in the web the product owner is displayed in a warning tooltip (some of the database product has been provided by the producer blah)

Instead of the lock icon we could use an info icon, with an info dialog.

I would believe that all of this should be less prominent than on the web version and possibly at the bottom of the page or in a special tab if we follow the proof of concept design.

I thought the point was to say: that specific field cannot be changed as it is provided by the producer.
If we display a generic message and let the users (try to) change the values regardless, we'll still have the not-so-funny "background tasks do not work" complaints.