[FEAT] process-monitoring: let pause and resume the display of the "happy path"

[tbouffard]

Is your feature request related to a problem? Please describe.
#73 let reset the animation.
It should be useful to be able to pause the animation while showing the demo to an audience.

Describe the solution you'd like
Display buttons to let start and pause the happy path display.

Additional context
This probably will force us to change the way to style the path.
Currently, we apply all CSS class at startup, and the CSS rules trigger the animation at a the right time.
Here, we should let a process within the demo manages the execution. We could do something similar to what we do on the "case monitoring" use-case when we display the runtime executed path on the "Supplier Contact" process.
If possible, share most of the code

Notice that in the execution of the Supplier Contact process, the edge are managed through the ExecutionStep which relates to an activity. Here, we need to handle both the edge and the shape in the same way, as specific elements of the path i.e. an edge must have its own ExecutionStep.