Test - Highlight start and end nodes

[cathelest]

Is your feature request related to a problem? Please describe.
When testing, a Highlight start and end nodes , EG Red for start, blue for middle nodes, green at end,
Would be useful to ensure the node counts match the props,
This would also be useful in the case when people use pysical null pixels/famps to regenerate data, but forget to put them into xlights,

Describe the solution you'd like
An option to highlight start/end nodes, that way at a glance if i can see it lights up, has a red pixel (start) green pixel (end) I know im good.

Describe alternatives you've considered
Not sure how this could be done in sequencing, maybe a specific effect but not sure.

Additional context

If you think this is useless and a fringe case, then happy for you to can it,