If the service is sending messages from GOVUK, then its messages should
be prefixed with the service name. Right now this logic is:
- worked out separately in the admin app and API
- isn’t aware of multiple senders
This commit moves the logic to one place (the service model). It does
this in a slightly naive way, in that it only looks at the default
sender, not the actual sender of the message.
In the future this will go away because we’ll move it to being a setting
that’s controlled independently of the service name. But this is the
first step towards that.
fixup! Add prefix SMS with service name to service model