feat(back): Setting up uid to user

Right now the user is saved with a "email" as uid that is not a working email.

This merge request removes the fake email and adds a real feide mail and gives each user a uid.

Make sure to test the frontend fully before approve'ing a review

Co-authored-by: Sondre Alfnes sondre.alfnes@gmail.com

Closes #20 (closed)