TNL-782 provide frontend with JWT ID Token for communicating with notes-api

https://openedx.atlassian.net/browse/TNL-782

@jimabramson @polesye @olmar @jmclaus 
> is this test no longer necessary ?

We need anonymous user id for batch notes creation, but we didn't find the way how to generate it in bok-choy tests. That's why we removed user validation from stub service and that's why this test is no longer necessary.