We want to be able to control who can access a template via roles.
I added this feature on the TeamAccess model assuming that the teams
to which a user belongs can be retrieved via a `get_teams` method on
the user model. The idea is that this method will get the teams either
via a call to an external API or directly from the OIDC token upon
user login. This list of teams will probably have to be cached for
each user.
