Attempt to define which resource types should be allowed within which content types

[andrewjbtw]

Structural metadata determines how objects will display on the purl. The content type determines which viewer will be displayed, and the resource types plus the organization of files under resources shapes how the content will be displayed.

We should be able to define which resource types can or cannot be used with which content types. For example, a resource type of "page" will only work within the content type of "book". A "page" within an "image" content type will result in an error message in the sul-embed viewer.

If we can define the allowable resource types for each content type, we can validate resource type selections when submitted to SDR and prevent invalid settings from being accessioned. It may take some trial and error to work out what is and is not supported currently in the system. Our method of setting these definitions and validations should be flexible enough to accommodate changes to how the sul-embed viewer displays content.