Allow Playing Individual Sounds with the /playsound Command

For the longest time we've been unable to play individual sounds with the /playsound command, especially ones with multiple variants.

One example of this would be the cave sounds. We have many of them, but we can't play individual ones on repeat, it's limited to playing a random one. It'd be nice if we were allowed to play individual ones like /playsound ambient.cave.3 for example.