Be able to configure a sound to play when a player gets a /msg

[ZepsiZola]

I feel like we should be able to configure a sound for when a player gets a /msg.
Like it would be super useful if you have the game running in the background and you get a 'ding' and realize you have been messaged in the game.

The config in config.yml could look something like
msg_sound: '' for no sound and msg_sound: 'SOUND' to configure a specific sound.

[osfanbuff63]

In VentureChat's msg system, this happens, and I've always wanted it to be a part of EssentialsX's msg system, although for sure optionally.