Add instance name to NodePinConfig

[huebl]

Add instance name to NodePinConfig class.

ToDo: PiXtendBaseServer::createNodeContext

1. create context name and find assigned hardware context a) instance name not emptry in NodePinConfig: use instance name from NodePinConfig object to create context name b) instance name empty: use instance name from class PiXtendBaseServer class to create context name

https://github.com/ASNeG/OpcUaPiXtendServer/blob/Release1/src/OpcUaPiXtendServer/OpcUaServer/PiXtendBaseServer.cpp#L150