[android] Add OnLoginSuccess callback to URLOpener interface (#4492)

The callback will be fired once login -> internal.Login
completes without errors

client/android/login.go

@@ -33,6 +33,7 @@ type ErrListener interface {
 // the backend want to show an url for the user
 type URLOpener interface {
 	Open(string)
+	OnLoginSuccess()
 }
 
 // Auth can register or login new client
@@ -181,6 +182,11 @@ func (a *Auth) login(urlOpener URLOpener) error {
 
 	err = a.withBackOff(a.ctx, func() error {
 		err := internal.Login(a.ctx, a.config, "", jwtToken)
+
+		if err == nil {
+			go urlOpener.OnLoginSuccess()
+		}
+
 		if s, ok := gstatus.FromError(err); ok && (s.Code() == codes.InvalidArgument || s.Code() == codes.PermissionDenied) {
 			return nil
 		}