Daemonization of Modbus/TCP connection manager

[iomz]

Once we find a way to daemonize the xArm connection handler, we will implement server command to start establishing the connection with an xArm robot.

[iomz]

I will try to finish this by the end of this week (contrary to my plan to do it last weekend).

[iomz]

After refreshing my C++ knowledge, the idea is not that easy with any IPC solution. Over the course I also discovered the raw Modbus socket (the UxbusCmdSer class) is already implemented and can be used with is_tcp_ = false – this makes the planned raw Modbus latency evaluation on the control box easier.

Any, I'll attempt to achieve this with gRPC instead – once and for all this will be my first complete gRPC project.