We want to replace the value `None` for
service.allowed_broadcast_provider with the value of "all". As a first
step, we need to allow both values. Once notifications-admin has been
changed to pass through "all" and all the data in the database has been
updated, we can update the code to stop supporting both values.
We are using the `set_broadcast_service_type` route to make changes to
service objects. However, we had forgotten to add the `version_class`
decorator to it which will mean the changing of a service going from
training to live mode will also be recorded in the services_history
table for free. Whilst not essential, this easy change makes things more
consistent for how we update other services.
We accidently were removing the ability for a service to do email auth
if it was a broadcast service with email auth. This fixes it.
Note, it might be up for debate later whether we let broadcast services
use email auth (I think we should) so this might change in time, but we
will fix this bug regardless.
Note, worth glancing at `SERVICE_PERMISSION_TYPES` which contains a list
of permissions that a service might have to make sure I haven't missed
any others. The one that looks potentially dodgy is the
`EDIT_FOLDER_PERMISSIONS` permission but I can't see this being used
anywhere in the API or the admin app so think it is likely now defunct
and a user level permission so we don't need to worry about it.
