Is your feature request related to a problem? Please describe.

I want to create a UGS item with Unlisted visibility. Because when the visibility mode is Private, when requesting to download this item via Item.Download, AccessDenied is returned.

Describe the solution you'd like
Add to Steamworks.Ugc.Editor
WithUnlistedVisibilites() with access to RemoteStoragePublishedFileVisibility.Unlisted flag.