Draft: Resolve "SysML Exporter"

After enabling them you should find with a right click on a fileproject a section of new context menu buttons. Mark the fileproject and selected other viewpoints to extract the viewpoints as packaged elements as uml model along with their corresponding SysML elements generated. If the selection of viewpoints is not valid, the option for extraction is not shown. Example: Selecting an Allocation table, but not the corresponding component and task architecture. (Here you are extracting references into a SysML file, where the referenced elements would not be present)

Closes #4223 (closed)