Field list: add a Download CSV button

Problem/Motivation

As a content model designer, I need to export a filtered set of information from the Content Model Fields list so that I can manipulate it in other programs.

For instance, as I am working on a content specification for a new content type, I may want to pull all the fields from a similar content type to use as a starting point.

Steps to reproduce

Proposed resolution

The "Content audit tools" on cms.va.gov allows users to export a filtered list to CSV. Something similar would be helpful here.

Remaining tasks

User interface changes

API changes

Data model changes