3rd-party RPCh exit node runners

[tolbrino]

A 3rd party must be able to run a RPCh exit node and be added within the RPCh network. The exit node should receive traffic. The exit node must be monitored like any other exit node to ensure platform availability.

Definition of Done

• exit nodes can be run by 3rd parties
• these exit nodes can be registered in the RPCh platform and used by end-users