ENH: torch: allow negative indices in take and take_along_axis

[ev-br]

fixes #360

A matching test update: data-apis/array-api-tests#397

[mdhaber]

The matching test is exactly what I'd like to see. How can we see that torch passes the test with this change?

I'm kicking myself, but it looks like I didn't take note of where I experienced this, so I can't provide a test of where this came up in the wild, but the solution and tests LGTM.

[ev-br]

How can we see that torch passes the test with this change

Locally one incantation is (run from the source tree of the array_api_tests clone):

ARRAY_API_TESTS_SKIP_DTYPES=uint16,uint32,uint64 ARRAY_API_TESTS_MODULE=array_api_compat.torch pytest array_api_tests/test_indexing_functions.py::test_take_along_axis -v --max-examples=10_000 -s

On CI, we'll need to land the array-api-tests fix first, and rerun the CI here to pick up the updated master branch of array-api-tests.

[mdhaber]

Oh, OK. Well the test change looked good, so I'll see when it runs here.