Distributed Hash Table, API-Access, Protocol Fixes, Unit Test Fixes

This merge request accumulates the work I've done:

1. Implementation of the Distributed Hash Table (DHT) UseCase(s)
2. Fixing the Tests by providing additional mocking and some shady interface creation (This should probably be fixed in the future with lazy evaluation)
3. Exposing parts of the DHT via a REST-Server written in Axum:
   • Documentation of the API using Swagger
   • fetch/store (including routing to NodeId or Hash as destination), local-hashtable (stored keys on the node)
4. Some fixes to the protocol to bring it closer to the simulation. Keep in mind this is currently wip.
5. Implementing the ability to route messages marked as overlay message automatically to the desired overlay hop using the ForwardProtocolMessage use-case.