Add new Beetleburst script option for Coldworm.js

Beetleburst is a rarely run superunique in Far Oasis with a treasure
class level of 87 and a monster level of 79. While his low monster level
detracts from his item table, he's so quick to kill that I added him
onto running Coldworm.

Patch Details:
- [x] Updated Coldworm.js to find and kill Beetleburst (preset 747).
- [x] Updated Config.js and all class templates to include the new
Config.Coldworm.KillBeetleburst option.