[auth] useEmulator

[radvansky-tomas]

Can you please expose useEmulator() method to allow auth emulator for all platforms?

https://firebase.google.com/docs/emulator-suite/connect_auth

firebase.auth().useEmulator('http://localhost:9099/');
Auth.auth().useEmulator(withHost:"localhost", port:9099)
FirebaseAuth.getInstance().useEmulator('10.0.2.2', 9099);

[nipunasudha]

+1

[newit-huytt]

+1

[Salakar]

PR is ready for testing, see the description if you'd like to try it out and give feedback: #4263

[deep-randhawa]

Any updates on this?