Proxy Update

Basically I've pulled the stuff from the main branch into the proxy, so it's updated to 4.21 at this point.

Furthermore spigot now relays the player IPs directly to the server when you use spigot in combination with BungeeCord. So I've added a check (using the metrics class for now according to @md_5) if we're running on a spigot server -> do not check if the players IP is the known proxy IP.
This fixes MCBans disabling itself as soon as a player connects.

And I've removed some old unused imports and stuff, so there are no issues on compile time.

Hope you like it.
Regards and thanks for the plugin for sure!
DerFlash