Add Image / Document / Video as ContentTypeFields

Similar to the other field types, it would be nice to have the ability to drag an control on the form designer to represent an image/document/video picker control.

I think the best way to do this is to have a system generated ContentType for Images, Documents, Video and each of these are really just a piece of content that is managed by the system and thus should be contained in (or at least accessible to) the StructuredContent module. Then, we can build a UX for picking an item from the collection. Should also have some capability to upload a new file to the collection.