[REFACTOR] Use the new flow/flownode links from the BPMN Semantic in the "Predictions" demo

[tbouffard]

Note: done as part or after #260

Currently, the demo list all edges and shapes that need to be blurred. They correspond to the already executed paths.
We could only reference the Shapes and deduct the edges from the incoming/outgoing data returned by the BpmnElementsRegistry APIs. We could also store the Edges and get the related Shapes from the sourceRef/targetRef.

The new information are available as of https://github.com/process-analytics/bpmn-visualization-js/releases/tag/v0.31.0 and have been used in the draw-path demo (see #468).