Store level data in a BlobAsset instead of a ScriptableObject

[cdwfs]

https://docs.unity3d.com/Packages/com.unity.entities@0.16/api/Unity.Entities.BlobBuilder.html

A blob asset is an immutable data structure stored in unmanaged memory which can contain blittable data, as well as structs and arrays (of blittable data), and can also contain strings in the form of BlobString. Since blob assets can be stored in binary format, they can be deserialized much more quickly than OOP assets such as ScriptableObjects