Random sorting

[evergreenbear]

Hi,
I want to preface this by saying that this is both my first PR to any project and my first time doing anything with Javascript. However it is very much working (for me, at least) on both Firefox and Chromium.

This adds a new sorting option, random, that shuffles the contents of the directory in a unique order each time it is selected.

I imagine there are likely changes that still need to be made for this to be production-ready which I had not managed to catch, but I figured I got somewhere and this may still be useful.
I modified make-sfx.sh because cp would error on that command without -r on the system I was using to build (AlmaLinux amd64), and the script would not finish.

This PR complies with the DCO; https://developercertificate.org/

[9001]

Hey :>

I'm curious to hear the reason you want to add this; what's the usecase?

[evergreenbear]

Truthfully, my use case is to randomly sort albums of old photos to look through for fun, though I imagine this would be more useful if used in conjunction with a slideshow feature for e.g. turning an old device into a digital photo frame