Transfer SOA basics/plugin into AF3 plugins for next release version

Background: For another project we have implemented some first extensions of AF3 for service-oriented architectures (SOA). This includes an own editor/view based on the component architecture but now with the possibility to add/manage subscriber and publisher and have them visually connected if they belong to the same topic.

Goal: Clean up current SOA files/code (https://git.fortiss.org/af3/soa) and add it as a AF3 plugin to have it included into the usual build process of AF3.

Test:

• Create an AF3 project
• Create a component architecture
• Observe that there is no possibility to select the SOA view or the SOA elements like publisher and subscriber
• Turn on "Expert View"
• Reload component architecture view
• Observe that the SOA view is now loaded directly for the component architecture and that you can add subscriber and publisher to components
• Observe also that if a publisher and a subscriber have the same topic name, e.g., "topic_test", a blue line will be visible between them to indicate a topic connection (maybe a refresh of the view/editor is needed)