Core/Battlegrounds: Implement Arathi Basin from Battle for Azeroth

Port From (https://github.com/TrinityCore/TrinityCore/commit/cc08aa8e249c5cd33f6b09a766cf6131c42566b9)

Source/Game/BattleGrounds/BattleGround.cs

@@ -1851,7 +1851,7 @@ namespace Game.BattleGrounds
         uint GetPlayersSize() { return (uint)m_Players.Count; }
         uint GetPlayerScoresSize() { return (uint)PlayerScores.Count; }
 
-        BattlegroundMap FindBgMap() { return m_Map; }
+        public BattlegroundMap FindBgMap() { return m_Map; }
 
         Group GetBgRaid(Team team) { return m_BgRaids[GetTeamIndexByTeamId(team)]; }
 

Source/Game/BattleGrounds/BattleGroundManager.cs

@@ -5,6 +5,7 @@ using Framework.Constants;
 using Framework.Database;
 using Game.BattleGrounds.Zones;
 using Game.BattleGrounds.Zones.AlteracValley;
+using Game.BattleGrounds.Zones.ArathisBasin;
 using Game.BattleGrounds.Zones.EyeofStorm;
 using Game.DataStorage;
 using Game.Entities;