feat(layers): add FAA drone restrictions airspace layer

Show US prohibited and restricted special-use airspace from the keyless
FAA SUA FeatureServer as an off-by-default Infrastructure layer, with
share-link token 3 and an informational-only disclaimer.

src/app/sourceComposition.js

@@ -46,6 +46,7 @@ export const CATALOG_SOURCE_CONTRACTS = Object.freeze({
   cyclones: contract(['weather-cyclones'], ['getSnapshot']),
   earthquakes: contract(['earthquakes'], ['getSnapshot']),
   'fire-perimeters': contract(['fire-perimeters'], ['getSnapshot']),
+  'drone-airspace': contract(['drone-airspace'], ['getSnapshot']),
   cables: contract(['telegeography-submarine-cables'], ['fetch']),
   transit: contract(['transit'], ['requestSnapshot', 'getHistory']),
 });