chore: Test empty local storage (#1123)

* Test empty local storage

* Additional ignore files for coverage

* Ignore unused symbol for test coverage

* Add mock OTP test

* add deprecation flag on ReturningOption

Author: dshukertjr

.gitignore

@@ -78,3 +78,5 @@ packages/**/pubspec.lock
 !**/ios/**/default.mode2v3
 !**/ios/**/default.pbxuser
 !**/ios/**/default.perspectivev3
+
+/packages/*/coverage

packages/gotrue/lib/src/broadcast_stub.dart

@@ -1,3 +1,4 @@
+// coverage:ignore-file
 import 'package:gotrue/src/types/types.dart';
 
 /// Stub implementation of [BroadcastChannel] for platforms that don't support it.