DOC: Remove dependency on sphinx_autodoc_typehints

[jakevdp]

sphinx_autodoc_typehints does not have any support for declaring type aliases (see tox-dev/sphinx-autodoc-typehints#132 and tox-dev/sphinx-autodoc-typehints#284). The only option is using their typehints_formatter config, which we probably shouldn't use because it breaks sphinx cacheing (see #20872)

The net result is that aliases like ArrayLike and DtypeLike are expanded into their full unions in our docs, which makes for a poor user experience. For example: here are the current jax.lax.argmin docs:

This PR removes the sphinx_autodoc_typehints extension, and instead uses sphinx's native typehint handlers; the result is this:

I have tried unsuccessfully to figure out how to make jax.typing.ArrayLike and jax.typing.DtypeLike link to their documentation page, but I think this is better than the current version.