1. axis_types now takes a `AxisTypes | tuple[AxisTypes, ...] | None`. It doesn't take a dictionary anymore
2. `jax.make_mesh` also takes the same `axis_types` tuple as in point 1.
PiperOrigin-RevId: 736360041
Previously, we represented a missing arg name with `None`,
and a missing result path with the empty string. We now
adopt the same convention for arg names and use empty strings.
This simplifies the typing, and prevents the string "None" from
appearing in error messages.
I changed how we encode the result paths. Previously for a
function that returns a single array the path was the empty
string (the same as for an unknown path). And for a function
that returns a pair of arrays it was `([0], [1])`. Now we
add the "result" prefix: `("result",)` for a function returning a
single array and `(result[0], result[1])` for a function returning
a pair of arrays.
Finally, in debug_info_test, I removed the `check_tracer_arg_name`
so that all spied tracers are printed with the argument name they
depend on.
