Add periodic entity cleanup task & new task system

[Lyfts]

The old task system was very lackluster and has been replaced with a more flexible system, tasks in this sense are just an easy way to define something we want to run at a given interval/at x time/x time from now.

A new cleanup task has been added that will remove the entities defined in config from the world at a given interval. Auto Shutdown & Backups have been converted to the new task system as they are perfect candidates for it and previously had code sprinkled in various classes to control the time that they should run.

Also fixes player heads drawing incorrectly on some guis (I'm too lazy to make a seperate pr) Before:

After:

Closes https://github.com/GTNewHorizons/ServerUtilities/issues/77

[github-actions[bot]]

Warning: 2 uncommitted changes https://github.com/GTNewHorizons/ServerUtilities/pull/79