MEDIUM: config: centralize handling of SSL config per bind line

MEDIUM: config: centralize handling of SSL config per bind line

SSL config holds many parameters which are per bind line and not per
listener. Let's use a per-bind line config instead of having it
replicated for each listener.

At the moment we only do this for the SSL part but this should probably
evolved to handle more of the configuration and maybe even the state per
bind line.