entityList type media files should be treated as entity lists

[seadowg]

If a mediaFile in the manifest has a type attribute equal to entityList, the media file should be treated as an entity list. This means:

• Entity lists should be consistent between forms (as in Make sure that entity lists are consistent between follow up forms #6029)
• Registration and update forms should create/update entities locally (assuming other conditions for local entities are met)
• Entities in the list should be visible in the experimental entity browser

This will replace the manual route for adding entity lists, and people wanting to try out offline entities post this change will have to use a newer server.