feat(search): compose Google and Photon through an explicit provider service

src/search/index.js

@@ -0,0 +1,3 @@
+export { createPlaceSearch, unavailablePlaceSearch } from './placeSearch.js';
+export { createGoogleGeocoder, normalizeGooglePlace } from './google.js';
+export { createPhotonGeocoder } from '../keylessGeocoder.js';