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/Maps/Map.cs

@@ -3228,19 +3228,6 @@ namespace Game.Maps
             return Global.DB2Mgr.GetMapDifficultyData(GetId(), GetDifficultyID());
         }
 
-        public ItemContext GetDifficultyLootItemContext()
-        {
-            MapDifficultyRecord mapDifficulty = GetMapDifficulty();
-            if (mapDifficulty != null && mapDifficulty.ItemContext != 0)
-                return (ItemContext)mapDifficulty.ItemContext;
-
-            DifficultyRecord difficulty = CliDB.DifficultyStorage.LookupByKey(GetDifficultyID());
-            if (difficulty != null)
-                return (ItemContext)difficulty.ItemContext;
-
-            return ItemContext.None;
-        }
-
         public uint GetId()
         {
             return i_mapRecord.Id;