Core/GameObjects: Use serverOnly property of GameObjectTemplate for all types that have it, not just spell focus

Port From (https://github.com/TrinityCore/TrinityCore/commit/7df4f5b2856af9b8eb2af83f827915ac28e3db3a)

Source/Game/Entities/GameObject/GameObject.cs

@@ -1295,7 +1295,7 @@ namespace Game.Entities
             if (base.IsNeverVisibleFor(seer))
                 return true;
 
-            if (GetGoType() == GameObjectTypes.SpellFocus && GetGoInfo().SpellFocus.serverOnly == 1)
+            if (GetGoInfo().GetServerOnly() != 0)
                 return true;
 
             if (GetDisplayId() == 0)

Source/Game/Entities/GameObject/GameObjectData.cs

@@ -677,6 +677,15 @@ namespace Game.Entities
             }
         }
 
+        public uint GetServerOnly() => type switch
+        {
+            GameObjectTypes.Generic => Generic.serverOnly,
+            GameObjectTypes.Trap => Trap.serverOnly,
+            GameObjectTypes.SpellFocus => SpellFocus.serverOnly,
+            GameObjectTypes.AuraGenerator => AuraGenerator.serverOnly,
+            _ => 0,
+        };
+        
         public uint GetSpellFocusType()
         {
             switch (type)