Core/Spells: Implemented SUMMON_PROP_FLAG_PERSONAL_GROUP_SPAWN

Port From (https://github.com/TrinityCore/TrinityCore/commit/2398c1e23c57cf5b6ac778b09a09d28e2704fd75)

Source/Game/Entities/Object/WorldObject.cs

@@ -1113,6 +1113,11 @@ namespace Game.Entities
             if (_privateObjectOwner == seer.GetPrivateObjectOwner())
                 return true;
 
+            Player playerSeer = seer.ToPlayer();
+            if (playerSeer != null)
+                if (playerSeer.IsInGroup(_privateObjectOwner))
+                    return true;
+
             return false;
         }
         

Source/Game/Entities/Player/Player.Groups.cs

@@ -149,6 +149,21 @@ namespace Game.Entities
             }
         }
 
+        public bool IsInGroup(ObjectGuid groupGuid)
+        {
+            Group group = GetGroup();
+            if (group != null)
+                if (group.GetGUID() == groupGuid)
+                    return true;
+
+            Group originalGroup = GetOriginalGroup();
+            if (originalGroup != null)
+                if (originalGroup.GetGUID() == groupGuid)
+                    return true;
+
+            return false;
+        }
+        
         public void SetGroup(Group group, byte subgroup = 0)
         {
             if (!group)