Hide catalogue item from catalogue

Bigpicture project would like to have an option to have catalogue items that are not visible in the Catalogue page but they can still be applied for with a link.
Catalogue items would show normally in the administration page.
Currently disabling hides the item from the catalogue, but new applications cannot be submitted to disabled catalogue items.

API side?

The issue names no files, tests, or entry points. Start by tracing catalogue visibility, administration display, and application submission through the API, then verify that an item can be hidden from the public Catalogue while remaining visible to administrators and applicable through a direct link.

Written by the indexing model from the issue text.