Core/Items: Item bonus generation improvements

* Pass ItemContext to item creation wherever possible
* Support scaling item levels with m+ keystone levels (not used currently)
* Fixed item link validation when client sends it as default uninitialized bonus list with context only
* Support scaling items depending on current active season (seasons not implemented)
* Implemented content tuning redirection
Port From (https://github.com/TrinityCore/TrinityCore/commit/0fb8765a6638fd947b59fce44d5c31251d0cdadd)

Source/Game/Handlers/MailHandler.cs

@@ -585,8 +585,8 @@ namespace Game
                 return;
             }
 
-            Item bodyItem = new();                              // This is not bag and then can be used new Item.
-            if (!bodyItem.Create(Global.ObjectMgr.GetGenerator(HighGuid.Item).Generate(), 8383, ItemContext.None, player))
+            Item bodyItem = Item.CreateItem(8383, 1, ItemContext.None, player);
+            if (bodyItem == null)
                 return;
 
             // in mail template case we need create new item text