Generic dungeon ambience loop

[Arcanorum]

A generic background loop for any dungeons that do not have a specific one to use.

Should be appropriate for dingy underground themed dungeons, which is most of them.

Acceptance criteria

• When a player enters a dungeon instance, a generic dungeon background loop should start.
• When the player leaves a dungeon instance, the loop should stop.

[Arcanorum]

The vampire island overworld is suitable for this purpose.