IO Setup register actual values

** Summary**

Be able to see the current value of the register variables in the IO Setup tab.

** What is it?**

** Why is it needed?**
It would help during commissioning when programming with the PLC. Currently what I do is to create a script with all the variables and read them continuously. After that I can see their value in the program tab variable list.

It would be nice to have this by default in Polyscope