Convert type_utils.py to use arraylias

[DanPuzzuoli]

Summary

This PR deletes type_utils.py; most functionality is no longer needed, and the two functions that were kept are moved to models/models_utils.py.

Details and comments

Details of what happened to the contents of type_utils.py:

• The functions to_array, to_csr, to_BCOO, and to_numeric_matrix_type have been deleted, along with their tests.
  • A few tests throughout the package that were still using to_array unnecessarily have been changed.
  • ScipySparseVectorizedLindbladCollection in operator_collections.py still had a final use of to_csr to remove. I modified the vectorized lindblad classes to no longer need this function, and ended up translating a test case for to_csr handling of qutip Qobj types into a test case for unp.asarray.
• The StateTypeConverter, along with its tests, have been completely deleted.
  • This class was originally written to handle a general type translation problem, but we didn't end up needing/using it, and in the end it was only used in a single location solvers/scipy_solve_ivp.py.
  • In light of the above, I've deleted the class and added a couple of much-simpler helper functions directly to solvers/scipy_solve_ivp.py.
• The last remaining functions, vec_commutator and vec_dissipator, are only used in models/operator_collections.py. As such I've move type_utils.py -> models/models_utils.py.

Other changes:

• Modified test_jax_transformations.py to no longer use Array.
• All of the arraylias changes have led to slight modifications to how lists of CSR matrices are stored (internally, models store them as numpy object arrays with csr_matrix entries). When returned to a user, they used to return as a list of csr_matrix entries, but now they just return the numpy object array. As such I've had to modify code in a few places that expect a list. These are very minor and sprinkled throughout the package.

Test command (now we can just run all tests! :) ):

python -m unittest discover test

The whole repo should now also pass linting.

[to24toro]

Thank you. I think the code becomes now very sophisticated.
I only request a great minor change.

[to24toro]

Thanks. LGTM!