Port is-supported-script expression to native

[ChrisLoer]

Port of mapbox/mapbox-gl-js#6260, to address mapbox/mapbox-gl-js#5807 (specifically: to make it easier to design styles that will use "local language" when possible but fall back to transliterations or another language when we can't render the local language).

This should be simpler on the native side, since we don't have to worry about whether the rtl-text-plugin is in use.

/cc @anandthakker @nickidlugash @1ec5