Feature Request: Add not applicable to IEC-62443-4-2 checklist

[hydraconis]

It would be great to have one or two more colors to show:

• that a requirement is not applicable (e.g. grayed out)
• that a requirement is fulfilled by the the system integration (e.g. yellow, blue)

[SecSimon]

This feature is implemented in TTModeler Pro

There are multiple predefined states for a requirement. Users can changes these states (color, icon) and create their custom states.