Generate the DI information automatically

When opening an bpmn file without DI information(the bpmndi:BPMNDiagram section), there will be an error. If the editor or viewer can generate the DI information automatically and display the diagram correctly, that will be great.

Expected Behavior

Actual Behavior

Steps to reproduce the Behavior

open a bpmn file without DI information. You can manually delete the bpmndi:BPMNDiagram element and all its descendants from a bpmn file generated by the bpmn editor