NuRV ORBIT2 - create/shutdown twin

[mortenhaahr]

Exemplify more clearly how the NuRV ORBit2 example is used as an external service.
I.e., have an example that will instantiate ORBit, run a twin instance, shut it down, run another twin instance, shut it down, and shut down ORBit.
Showcasing how it is truly an external service that the DTs can use.

Edit: I added this issue to ensure that we do not forget to implement it after tutorial submission.