This allows to use `people` as an identity provider using
OIDC and local users.
This commit is partial, because it does not manage a way to
create "local" users and the login page is the admin one, which
can't be used for non staff users or login with email.
To be able to provide a SIRET in the ProConnect IdP process
we need to be able to link a mail domain to its organization.
For now this is not mandatory, as we can't detect the organization
and need a frontend process to clarify it.
Create a Django admin action to allow retrieval of
the expected domain configuration from dimail.
These values shouldn't change unless external
intervention occurs. An admin command seems sufficient to handle
hypothetical changes.
mark local_part and domain as read-only fields in admin,
in order to prevent mistakes/temptation. For now, if an local part
needs modification, you can simply delete/recreate the email you want.
Changing the domain is a bigger operation that cannot
be settled simply by changing it Django db.
Rename member role to viewer role for MailDomainAccess.
A viewer is only allowed to see list of mailboxes
created for a domain. It makes more sense to name it viewer.
