Speed up state space creation

[segsell]

Currently, the creation of large state spaces is very slow.

To-Do:

• Separate create_state_space from get_solve_function so that the state space can be created outside of jax. E.g. with numba
• If we want to use numba, we need to switch from the options dict to namedtuple

[MaxBlesch]

Done with moving away from the old per period creation.