Custom Filter Sound Variations

The command CustomAlertSound currently only apply to a single sound file. I suggest to give the command the ability to play a random sound under the directory it is given, so we can have a bit of variation.

PS. If I try to brute force it in the .filter file, it would result in a massive file of size in MBs(basically making a single filter block to only pass one item), I'm not sure how the game would react to so many if-then operations, but it sure will have quite some performance impact