Fixes (adds) stringed coin functionality with gashapons and candy machines

Created by: Skullyton

Fixes #7536 and #7381 (closed)

To keep it balanced, made it so that you're more likely to lose your coin on them than with a regular vending machine, because of the possibility for ultra antag fun by emagging a candy machine, or ohshitwhyaretheresomanytoys with gashapons.

Also scanned through reported issues with these two machines and its products, and fixed a typo.