[js][firestore] added `enableLogging(boolean)` method

lib/modules/firestore/index.js

@@ -2,6 +2,8 @@
  * @flow
  * Firestore representation wrapper
  */
+import { NativeModules } from 'react-native';
+
 import ModuleBase from './../../utils/ModuleBase';
 import CollectionReference from './CollectionReference';
 import DocumentReference from './DocumentReference';
@@ -141,4 +143,9 @@ export default class Firestore extends ModuleBase {
 export const statics = {
   FieldValue,
   GeoPoint,
+  enableLogging(bool) {
+    if (NativeModules[Firestore._NATIVE_MODULE]) {
+      NativeModules[Firestore._NATIVE_MODULE].enableLogging(bool);
+    }
+  },
 };