Add test file for top_k functionality

[oleksandr-pavlyk]

This PR adds a test file with few basic tests for top_k. To be extended.

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[github-actions]

View rendered docs @ https://intelpython.github.io/dpctl/pulls/1938/index.html

[github-actions]

Array API standard conformance tests for dpctl=0.19.0dev0=py310h93fe807_332 ran successfully.
Passed: 894
Failed: 2
Skipped: 118

[oleksandr-pavlyk]

One test failed on CPU:

=========================== short test summary info ============================
FAILED tests/test_usm_ndarray_top_k.py::test_topk_1d_largest[255-i1] - assert usm_ndarray(False)
 +  where usm_ndarray(False) = <function all at 0x7f1fbb4b6d40>(usm_ndarray([...], dtype=int8) == usm_ndarray([...], dtype=int8)
 +    where <function all at 0x7f1fbb4b6d40> = dpt.all
    
    Full diff:
    - usm_ndarray([1, 1, 1, 1, 1], dtype=int8)
    ?              ^  ^  ^  ^  ^
    + usm_ndarray([0, 0, 0, 0, 0], dtype=int8)
    ?              ^  ^  ^  ^  ^)
==== 1 failed, 16051 passed, 1897 skipped, 8 warnings in 419.43s (0:06:59) =====

[oleksandr-pavlyk]

Interestingly, there is no issue when the test is run on Xeon:

$ SYCL_CACHE_PERSISTENT=1 ONEAPI_DEVICE_SELECTOR=opencl:cpu python -m pytest dpctl/tests/test_usm_ndarray_top_k.py
=========================================================================== test session starts ============================================================================
platform linux -- Python 3.12.4, pytest-8.3.1, pluggy-1.5.0
rootdir: /localdisk/work/opavlyk/repos/dpctl
configfile: pyproject.toml
plugins: cov-5.0.0
collected 143 items

dpctl/tests/test_usm_ndarray_top_k.py .............................................................................................................................. [ 88%]
.................                                                                                                                                                    [100%]

=========================================================================== 143 passed in 3.32s ============================================================================

[ndgrigorian]

Interestingly, there is no issue when the test is run on Xeon

And no issue when run on another (different) AMD CPU:

$ python -m dpctl -f
Platform  0 ::
    Name        Intel(R) OpenCL
    Version     OpenCL 3.0 LINUX
    Vendor      Intel(R) Corporation
    Backend     opencl
    Num Devices 1
      # 0
        Name                AMD EPYC 7R13 Processor
        Version             2024.18.12.0.05_160000
        Filter string       opencl:cpu:0

$ SYCL_CACHE_PERSISTENT=1 ONEAPI_DEVICE_SELECTOR=opencl:cpu python -m pytest dpctl/tests/test_usm_ndarray_top_k.py
================================================= test session starts ==================================================
platform linux -- Python 3.9.21, pytest-8.3.4, pluggy-1.5.0
rootdir: /home/ubuntu/repos/dpctl
configfile: pyproject.toml
collected 143 items

dpctl/tests/test_usm_ndarray_top_k.py .......................................................................... [ 51%]
.....................................................................                                            [100%]

================================================= 143 passed in 1.14s ==================================================

[github-actions]

Array API standard conformance tests for dpctl=0.19.0dev0=py310h93fe807_333 ran successfully.
Passed: 894
Failed: 2
Skipped: 118

[github-actions]

Array API standard conformance tests for dpctl=0.19.0dev0=py310h93fe807_334 ran successfully.
Passed: 894
Failed: 2
Skipped: 118