convert McCall job search I to JAX

[jstac]

Convert https://python.quantecon.org/mccall_model.html to JAX, using https://python.quantecon.org/mccall_model_with_separation.html as a model.

(For example, model data is stored in a class(NamedTuple).)

Be sure to check the surrounding text and adjust accordingly.

(For example, see "Note the use of [::1] in the array type declarations above.")

[shlff]

• convert the numba/numpy code to jax
• modify the surrounding text
• double-check grammar & math