[1.x][LT] Add forward, backward test for linalg.gemm2

[ChaiBapchya]

Description

Related PR: #18718

Checklist

Essentials

Please feel free to remove inapplicable items for your PR.

• Changes are complete (i.e. I finished coding on this PR)
• All changes have test coverage:
• Code is well-documented:
• To the best of my knowledge, examples are either not affected by this change, or have been fixed to be compatible with this change

[mxnet-bot]

Hey @ChaiBapchya , Thanks for submitting the PR
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[ChaiBapchya]

@mxnet-label-bot add [pr-awaiting-review]

[mseth10]

LGTM

[ChaiBapchya]

Test results:

python -m pytest -s --exitfirst --verbose tests/nightly/test_large_array.py::test_gemm2
==================================================== test session starts =====================================================
platform linux -- Python 3.7.7, pytest-5.4.3, py-1.9.0, pluggy-0.13.1 -- /home/ubuntu/gemm2_test_venv/bin/python
cachedir: .pytest_cache
rootdir: /home/ubuntu/chai-mxnet
collected 1 item

tests/nightly/test_large_array.py::test_gemm2 [23:35:35] ../src/base.cc:84: Upgrade advisory: this mxnet has been built against cuDNN lib version 7501, which is older than the oldest version tested by CI (7600).  Set MXNET_CUDNN_LIB_CHECKING=0 to quiet this
warning.
PASSED

======================================================================================================================== warnings summary ========================================================================================================================
/home/ubuntu/gemm2_test_venv/lib/python3.7/site-packages/nose/importer.py:12
  /home/ubuntu/gemm2_test_venv/lib/python3.7/site-packages/nose/importer.py:12: DeprecationWarning: the imp module is deprecated in favour of importlib; see the module's documentation for alternative uses
    from imp import find_module, load_module, acquire_lock, release_lock

-- Docs: https://docs.pytest.org/en/latest/warnings.html
============================================================================================================ 1 passed, 1 warning in 192.18s (0:03:12) ============================================================================================================

[mseth10]

@ChaiBapchya file conflicts need resolving

[ChaiBapchya]

Reran after adding shape check

python3 -m pytest -s --exitfirst --verbose tests/nightly/test_large_array.py::test_linalg
========================================================= test session starts =========================================================
platform linux -- Python 3.7.7, pytest-5.4.1, py-1.8.1, pluggy-0.13.1 -- /home/ubuntu/anaconda3/bin/python3
cachedir: .pytest_cache
hypothesis profile 'default' -> database=DirectoryBasedExampleDatabase('/home/ubuntu/chai-mxnet/.hypothesis/examples')
rootdir: /home/ubuntu/chai-mxnet
plugins: remotedata-0.3.2, openfiles-0.4.0, astropy-header-0.1.2, hypothesis-5.8.3, arraydiff-0.3, doctestplus-0.5.0
collected 1 item

tests/nightly/test_large_array.py::test_linalg [23:12:33] ../src/base.cc:84: Upgrade advisory: this mxnet has been built against cuDNN
lib version 7501, which is older than the oldest version tested by CI (7600).  Set MXNET_CUDNN_LIB_CHECKING=0 to quiet this warning.
PASSED

========================================================== warnings summary ==========================================================$
/home/ubuntu/anaconda3/lib/python3.7/site-packages/nose/importer.py:12
  /home/ubuntu/anaconda3/lib/python3.7/site-packages/nose/importer.py:12: DeprecationWarning: the imp module is deprecated in favour o$
 importlib; see the module's documentation for alternative uses
    from imp import find_module, load_module, acquire_lock, release_lock

-- Docs: https://docs.pytest.org/en/latest/warnings.html
============================================== 1 passed, 1 warning in 142.52s (0:02:22) ==============================================

[access2rohit]

LGTM!

[ChaiBapchya]

@mxnet-label-bot update [pr-awaiting-merge]