Consider removing client registry

[dorotaphanSiili]

Motivation: on the client side the client registry adds

• functionality of easy checking how many nodes we have and to which nodes they are added
• adds possibility of making in the future some complex features for managing the type of connection or load balancing (although no plans yet for it)
• adds constraint that no other object with the objectId can be in same registry for different nodes, the latter sink is not added and is not informed about it
• adds complexity, current class needs to keep in synch - for setting up, it has to do 2 step registration (separately adding node and sink object ) and for lifetime of the objects*, where just a map in clientNode would be enough, sink would link straight to clientNode

*we keep it as raw pointers in registry, we could be safer changing to weak_ptrs but that requires change for creating objects, they need to be created only with factory method as shared ptrs, where for clientNode I think it is ok, for objectSink, which is remoteInterface that feels wrong.

[w4bremer]

Has been discussed and decided not to implement for now. Can be re-opened later if necessary.