The app name in the SMS sent for phone auth is the localhost `127.0.0.1`

## Issue description
When using phone authentication, the SMS sent has `127.0.0.1` as the app name. Example:

## Context
The reCAPTCHA verification step is done on the localhost server and launched in aa WebView, which is causing auth handler to use the domain as an app name.

Phone authentication on the desktop implementation is using the Identity Platform REST API. On Firebase iOS and Android SDK, the auth handler `/__/auth/handler` can detect and verify the app scheme, for instance, [in the iOS SDK here](https://github.com/firebase/firebase-ios-sdk/blob/c7c01493517aeaa0e6c2aa5af5acbe76a19c998f/FirebaseAuth/Sources/AuthProvider/Phone/FIRPhoneAuthProvider.m#L648-L686), couple parameters sent which result in the correct app name being sent in the SMS.