Requires changing `generate-style-code` to treat 'formatted' as being the same as 'string' until gl-native gets 'formatted' support with https://github.com/mapbox/mapbox-gl-native/pull/12624. To make nitpick happy, PropertyFunction.java uses the latest "text-field" description from v8.json. It's technically correct, just kind of pointless since the "If a plain `string` is provided" clause will always be true.