Core/Battlegrounds: Added OnMapSet hook

src/server/game/Battlegrounds/Battleground.cpp

@@ -1449,7 +1449,10 @@ void Battleground::SetBgMap(BattlegroundMap* map)
 {
     m_Map = map;
     if (map)
+    {
         _pvpStatIds = sDB2Manager.GetPVPStatIDsForMap(map->GetId());
+        OnMapSet(map);
+    }
     else
         _pvpStatIds = nullptr;
 }

src/server/game/Battlegrounds/Battleground.h

@@ -494,6 +494,9 @@ class TC_GAME_API Battleground : public ZoneScript
             return &itr->second;
         }
 
+        // Called when valid BattlegroundMap is assigned to the battleground
+        virtual void OnMapSet([[maybe_unused]] BattlegroundMap* map) { }
+
     protected:
         // this method is called, when BG cannot spawn its own spirit guide, or something is wrong, It correctly ends Battleground
         void EndNow();