Some background - a 'campaign' is a thing set up by an admin on commons, and it's aimed at getting people to upload images based on a certain theme.
Here's a korean campaign from a while ago https://commons.wikimedia.org/wiki/Campaign:ko If you click on 'Upload' you'll be brought to the UploadWizard configured for that campaign
The configuration is setup on-wiki by the campaign admin - for example you can set it up so that images uploaded under a campaign can have a set of allowed licenses, or so that everything uploaded in a campaign will be put into particular categories.
Now that we've added support for 'depicts' statements, we want to provide (very basic, at first) support for depicts in campaigns. What this amounts to at the start is basically that a campaign admin can decide to turn 'depicts' support on or off.
They can do so by going to the campaign config page on-wiki and editing the json there. Here's an example on labs https://federated-commons.wmflabs.org/w/index.php?title=Campaign:without-depicts&action=edit - the `"depicts": false` here means that if you go to the UploadWizard page for the campaign there'll be no step to add/edit depicts statements. If you change that to `true` and save it then the user should be able to add/edit depicts statements in one of the steps in UploadWizard
 campaign creator can configure basic depicts support to be on or off for a campaign
(working example: https://federated-commons.wmflabs.org/w/index.php?title=Campaign:without-depicts&action=edit)
 user can click on a campaign link, upload 1 or more images, and as part of that process will get to a metadata step where they can enter 'depicts' tags for each image
(working example: https://federated-commons.wmflabs.org/wiki/Campaign:with-depicts)
 user can click on a campaign link, upload 1 or more images, and as part of that process will NOT get to a metadata step
(working example: https://federated-commons.wmflabs.org/wiki/Campaign:without-depicts)
Out of scope:
* default values for depicts
* requiring the user to enter depicts data