Core/Battlegrounds: Rework queues

* No more copies of Battleground classes
* FreesSlotQueues now have as key the MapId instead of queue id
* Random queues can now popup already busy specific battelgrounds (queues are NOT merged)
* Removed Holiday handling, this should already be handled in BattlegroundMgr::IsBGWeekend
Port From (https://github.com/TrinityCore/TrinityCore/commit/0ede6c155605da602b3bafaa3a1212d9f924759b)

Source/Game/Entities/Player/Player.Items.cs

@@ -6174,7 +6174,7 @@ namespace Game.Entities
             Battleground bg = GetBattleground();
             if (bg != null)
             {
-                if (bg.GetTypeID(true) == BattlegroundTypeId.AV)
+                if (bg.GetTypeID() == BattlegroundTypeId.AV)
                     bones.loot.FillLoot(1, LootStorage.Creature, this, true);
             }
             // For wintergrasp Quests