[Enhancement]: add a Skipped Frames HUD (or GUI) display

[bernie-laberge]

Discussed in https://github.com/AcademySoftwareFoundation/OpenRV/discussions/80

^{Originally posted by ggarra13 January 20, 2023} Currently, OpenRV has a play all frames option (by default) or a realtime option. It would be nice if the real time option showed the number of skipped frames in a HUD or somewhere in the timeline area.