Add whetstone sound effect

[tagniam]

The game currently has sound effects for attacking and healing, but no sound plays when the player uses a whetstone.

We'd like to use a sound effect like this to play when the player uses a whetstone: https://freesound.org/people/GameDevC/sounds/422832/

Please make sure you credit the original author in Sound.cpp!

[Shaedil]

Hey, I'd like to give this a try if you don't mind.

[tagniam]

@Shaedil Go for it! 👍