Bring back ReactNative

Author: schmidt-sebastian

packages/firebase/src/index.rn.ts

@@ -23,6 +23,7 @@ import '../database';
 // TODO(b/158625454): Storage doesn't actually work by default in RN (it uses
 //  `atob`). We should provide a RN build that works out of the box.
 import '../storage';
+import '../firestore';
 
 firebase.registerVersion(name, version, 'rn');