Finish Eclipse Ditto integration

[ctron]

This is a tracking issue for finish up the Eclipse Ditto integration.

• [x] Receive telemetry
• [ ] Desired state / commands
  • [ ] Outgoing events/commands
  • [ ] Examples
• [ ] Registry
  • [x] App C(R)UD
  • [x] Device C(R)UD
  • [ ] Map policies
  • [x] Make opt-in
• [ ] Proper multi-tenancy integration
  • [x] Limit creation of resources - https://github.com/eclipse/ditto/pull/1251
  • [ ] Limit access by namespace/application
• [ ] Chores
  • [ ] System tests
  • [ ] Documentation
  • [ ] Workshop