Implement reverse playlist

[ParticleCore]

Considering implementing this feature again if it is still feasible, it will allow playlists to play in the reverse order.

[ParticleCore]

Playlist reordering seems to be working correctly

Still need to finalize the button state, change the player functionality, and update the previous/next video indexes whenever the list order is modified.

[ParticleCore]

The feature should be complete. Unsure of what scenarios might be overlooked at the time, the platform has become quite complex over the years so there might be some things that were not addressed, or couldn't be addressed. Nevertheless, the basic functionality should be fully working:

One thing to note is I have no idea how it will behave with the new YT layout, I have not been able to get it once during my time implementing this feature, so it will be pushed and hopefully it will work as is with the new layout as well.

[ParticleCore]

Setting should be sufficiently self-explanatory