Allow limiting fields to specific countries/regions

[quincylvania]

There's the potential for certain advanced fields that only apply to particular countries such as a business's VAT number (see #6880 (comment)) or GNIS ID. Now that we've done #6941, looking up country codes is relatively free. Like presets, we could have countryCodes and notCountryCodes properties for fields.

[bhousel]

Oh hey! You beat me to this..
I'm working on a general way of representing these for other projects too (name-suggestion-index, osm-community-index, whatever we decide to do with editor-layer-index), and I'll have this working in the location-conflation project in the next few days.

👉 Would you consider a schema like:

locations: {
  include: [Array],
  exclude: [Array]
}

The arrays may contain anything that country-coder recognizes, but I'm also supporting other stuff too (like a example.geojson filename). This gives us the flexibility to support non-country-coded things like "Scotland" or "French-speaking Canada", which we need for some communities in OCI, or some brand extents in NSI.

[quincylvania]

@bhousel Sure, it'd be great to have more flexibility and take advantage of that project 👍

We can also switch the preset properties, though that will be a breaking change.