Use module WG tracking and add battlefield hooks

[Nyeriah]

Replace reliance on core GetPlayersInWarCount() with a module-owned _wgWarPlayers set for WorldGuard (WG) balancing, and add battlefield hooks to manage fake-team assignment lifecycle. Changes: add BATTLEFIELDHOOK_ON_PLAYER_ENTER_ZONE and BATTLEFIELDHOOK_ON_PLAYER_LEAVE_WAR; implement OnBattlefieldPlayerEnterZone to assign an alternate team only during active war (and skip already-faked players); implement OnBattlefieldPlayerJoinWar to handle fallback assignments and to insert players into _wgWarPlayers when they accept invites; implement OnBattlefieldPlayerLeaveWar to remove players from _wgWarPlayers; update OnBattlefieldPlayerLeaveZone to clear fake players and perform a safe GUID erase as a catch-all. These changes ensure balance decisions are based on clean, module-maintained state and avoid leaving stale entries in core battlefield structures.