These files are used by me (wez!) while hacking things together locally
as a non-privileged user (myself). They should not contribute to the
overall message accounting database. Let's give each instantiation a
separate temporary path.
To facilitate this, formatlize the `campaign:tenant@domain` naming
and add a helper type to parse and format that tuple of information
to make it easier to work with in the code.
Adjust the get_x_config events to accept those parameters.
A callback is used to resolve the config at the time that
we set up the destination site structure (eg: when we get the first
ready-to-send message for it, and again after it has idled out).
This is used in the example configs to enable "OpportunisticInsecure"
TLS mode so that we can successfully delivery over TLS to the
default self-signed TLS certs on the sink.
Wez Furlong
Mike Hillyer