Generating a list of fields for customization, similar to Table's Field formatting

[ChrisWilliams]

I'm updating a custom control and I was considering giving users some additional control over the formatting of their fields.  If you look at the Table control's Field formatting section, you can see that they display a list of fields (columns) and then users can specify options for each field.

How would I update capabilities.json to cause this select control to be displayed? I think I understand how 

enumerateObjectInstances might be structured, but not quite sure how to handle capabilities.json.

Thanks