[library] Allow generic lists

As an administrator, I would like the ability to create generic JSON-only lists that surface up in the library so my users have the ability to pick from different types of metadata (tags, authors, etc.).

## Additional Context
The original implementation of library implied that if library didn't know what a list was, it would drop out to a default KV style list behavior. The new library will simply load the JSON in an iframe when it doesn't know what it is.

Start by tracing the library's handling of known and unknown list types, then inspect how it currently falls back to KV-style lists. The work is done when an administrator can create a generic JSON-only list and the library loads that JSON in an iframe so users can choose metadata such as tags or authors.

Written by the indexing model from the issue text.