[RN] Disable the XHR backend on mobile

All language assets will need to be bundled.

react/features/base/i18n/i18next.js

 };
 
 i18next
-    .use(I18nextXHRBackend)
+    .use(navigator.product === 'ReactNative' ? {} : I18nextXHRBackend)
     .use(languageDetector)
     .use({
         name: 'resolveAppName',