Implement Update Checker

[lokka30]

A configurable async update checker should be implemented to remind users to update BlackWidow.

Configurability:

• Toggle the whole update checker.
• Toggle whether it runs on startup.
• Toggle whether it runs on a timer.
• Toggle whether it logs whether there are updates available.
• Toggle whether it informs players with permission (permission string to be decided later; enabled for operators by default).

Complete after:

• Release the resource to HangarMC #10, so we have something to check the version number from (would rather not use GH)