Add community member with anonymous persona

[dasaderi]

I was writing onboarding documentation for new community members and just realized a (or multiple) potential issue with adding PREreviewers who want to use their anonymous persona.

Questions for @thewilkybarki:

• When a PREreviewer asks to join a community, will both personas be added to it?
• When a PREreviewer is added to the community via the settings, will they belong to that community with both their personas?

If the answer to these is no, we need to re-think this workflow as if a PREreviewer wanted to post anonymously within a community, they would need to reveal their anonymous name to the moderator, which can be a problem.