Save System v1.8 Odin Serializer

• Removed internal Item allocation.
• Asset reference resolver now uses ushort instead of string. It has also been backported to the MessagePack version.
• AOT (IL2CPP) no longer requires you to create an ITypeProvider, except in very rare and unusual cases.

Update from the previous version requires you to add all asset references again. So, do NOT update if your game is in production and you do not want to break users' save files.