Partial support of `FlowUsage` graphical edge

[gcoutable]

Steps to reproduce

1. Import in a SysMLv2 Model the Camera example from here : https://github.com/Systems-Modeling/SysML-v2-Release/tree/master/sysml/src/examples/Camera%20Example
2. In a GV diagram import at least the ActionUsage takePicture
3. Display the action flow compartments
4. The two focus and shoot ActionUsage graphical nodes should be visible
5. If their inherited border nodes are not displayed, display them with the Manage Visibility menu

Expected result

According to the SysMLv2 specification, there should be a graphical edge representing the FlowUsage between the two inherited border nodes.

Actual behavior

No edge is displayed between the two inherited border nodes