Add subclass for decompressed arrays

Following [this comment](https://github.com/data-apis/array-api/discussions/968#discussioncomment-14350012), add a thinly wrapped native Blosc2 class for decompressed arrays, which are currently just plain NumPy arrays. Would have to support certain additional operations and comparisons (``==``, ``__array_namespace__()``), but it will inherit most of the useful machinery directly from NumPy.

Would have to change ``np.empty`` references for loading slices etc. from C functions in the code base, possibly some other things.

Start by tracing how decompressed arrays are created and where C functions use np.empty when loading slices. Review the existing native Blosc2 and NumPy array machinery before defining the subclass behavior. Done means decompressed arrays support ==, __array_namespace__(), the required additional operations and comparisons, with affected loading paths updated.

Written by the indexing model from the issue text.