feat: initialize demo for PathResolver

[tbouffard]

The demo provides the following features

• select and unselect shapes by clicking with the mouse. Highlight the shape on select by changing its style.
• a button lets compute the path based on selected shapes (infer edges with the current implementation of the PathResolver)
• changing the selected shapes and recompute the path highlights the edges accordingly
• a button lets clear all selected shapes and infer edges

covers #17

Video

demo_aa9ebef.mp4

[github-actions]

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