feat(user): add new property `status` to user profile

In `.config.json`, the default status for new users can be defined.
This allows people hosting their own portal to for example set the `default_status` to `AUTHORIZED`, in case they don't want to explicitly authorize each user manually.
Existing users will be migrated to the `default_status` (or `INITIAL`, if one is not defined).
Staff / PA will be migrated to `AUTHORIZED` in any case, to ensure access to the portal is still maintained.

Closes #215

Signed-off-by: martinfrancois <f.martin@fastmail.com>