Ability to Create Linked Item Types

Create a way to allow new Linked Item Types to be created. At a minimum, this should be something an Admin user can do, at best it's permissions-based that publisher/subscribers can create.

The primary use case here is to allow manufacturers to create linkages between items not only of their items but to their competitors' items (this would be dependent on how they are set in CX1 PIM - if they are just another subscriber account in the subscription program vs a whole new instance of CX1 PIM.