Feature Request: references should be able to include objects representing restriction objects/arrays

[joneubank]

To support the conditional restrictions work, we want to be able to store restrictions in references so that the complex restriction objects are reusable.

Currently, References must be a string, or an array of strings. A string in an array can be a tag pointing to another reference which will result in combing arrays together.

New Reference Rules

• references must be validated as a string, array of strings, restriction object, or array of restriction objects
• references that are an array of restrictions can use a reference tag as a value in the array, if that tag points to another restriction object or restriction array
• a reference tag pointing to a restriction object cannot be used in a code list (array of strings). the schema validation needs to return an error when this occurs