authn: Store legacy plugins prefix in module variable.

authn: Add docstring to function that discovers legacy plugins.

authn: Import legacy authentication modules and invoke their includeme.

authn: Load legacy plugin ID's from DB and log them.

migration: Increased database version.

migration: Add data migration of the users 'extern_type' attribute. - Folow up from renaming the auth_container plugin. - This migration renames the extern type for all users from 'container' to 'headers'

ldap-auth: fixed wrong Missing check

ini: fixed typo, remove debug style from production

ini: in CE repo we don't expose EE edition configuration.

ini: fixed a typo