core (xmpp): adapt message workflow to components: message workflow were not used for components so far. This patch activate it, normalise namespace to the client one to simplify parsing, and use SatXMPPComponent.sendHistory and SatXMPPComponent.receiveHistory to indicate if a component should store sent and received message in database (they both default to False). OTR plugin is deactivated for components. rel 367

these certificates are used for demo purpose only. Those must be the same as in
backend_e2e (they are generated there)