This PR fixes an issue where we would clobber the other JSON Schema
fields for any field that we attached a reference to.
This resulted in these fields (e.g., `buffer_font_family`,
`ui_font_family`) losing things like their descriptions.
The approach has been adjusted that references are now added in an
additive fashion, rather than overriding the entire schema object.
Release Notes:
- Fixed an issue where font-related settings in `settings.json` were
missing their descriptions.
Marshall Bowers
8b22f09b6f