Feature Request: random-order slideshow

**Describe the idea / solution you'd like**
The built-in image/video viewer is great (click on a picture or video, use left/right arrow to look through the rest of the media), however one particular feature I think it's missing is the ability to randomize the order of the images/videos when going through them.
This is a feature I'm pretty used to from most "gallery" apps and such, although I admit it's usually coupled with a slideshow (maybe that's a separate feature request?).

As for how this feature would work, I have a few ideas, and I'm not partial to any of them so hopefully other people can chime in with which one seems most reasonable:
- Given that the viewer goes through media in the same order the files are listed, maybe the most natural way to add this would be to add another sort order called shuffle?
- There's already a shuffle switch for the music player, maybe use it for the media viewer too? Or add a very similar, separate one?
- Add a toggle button (and/or keybind) at the top right of the viewer (along with the rest of them, like the rotate and sel buttons) with a shuffle icon, that toggles shuffle order?