Add social provider sign-in

amplify add auth     ## "amplify update auth" if already configured

? Do you want to use the default authentication and security configuration? 
    `Default configuration with Social Provider (Federation)`
? How do you want users to be able to sign in? 
    `Username`
? Do you want to configure advanced settings? 
    `No, I am done.`
? What domain name prefix you want us to create for you? 
    `(default)`
? Enter your redirect signin URI: 
    `myapp://`
? Do you want to add another redirect signin URI 
    `No`
? Enter your redirect signout URI: 
    `myapp://`
? Do you want to add another redirect signout URI 
    `No`
? Select the social providers you want to configure for your user pool: 
    `<choose your provider and follow the prompts to input the proper tokens>`

<queries>
  <intent>
      <action android:name=
          "android.support.customtabs.action.CustomTabsService" />
  </intent>
</queries>
<application>
  ...
  <activity
        android:name=".MainActivity" android:exported="true">
        <intent-filter>
            <action android:name="android.intent.action.VIEW" />
            <category android:name="android.intent.category.DEFAULT" />
            <category android:name="android.intent.category.BROWSABLE" />
            <data android:scheme="myapp" />
        </intent-filter>
  </activity>
  ...
</application>

Future<void> socialSignIn() async {
  try {
    final result = await Amplify.Auth.signInWithWebUI(
      provider: AuthProvider.google,
    );
    safePrint('Sign in result: $result');
  } on AuthException catch (e) {
    safePrint('Error signing in: ${e.message}');
  }
}