The idea is that we will marshal the payment, send it to the campsite’s
instance by email, and then unmarshal it as a booking, that way we can
have a one way replication from the internal to the public instance with
a way back to send the payments.
For testing purposes, i just create the booking in the same instance.
Had to change the booking relation’s permissions to allow insert from
a guest, much like for payments, because the notification from Redsys
comes as a guest connection. I need this even with all the
marshal/unmarshal shenanigans because not everyone will have an internal
instance, thus need to allow bookings from guest connections.
