MAGN-4745 Colour the nodes according to the delta state

The users have no idea of Node execution plan, when a value of a node is changed.

This fix address the node execution plan. When Show Node Execution is set on the Debug menu, 
users can see the nodes with Green boundary, meaning those nodes will be executed on the next run. 
Nodes will retain its original state after the run. 

- [ ] @lukechurch 
- [ ] @junmendoza 
- [ ] @ikeough 
Why does the implementation of a Preview class need to call UpdateGraphImmediate?