Add support for testing DIP dialect's 2D correlation op with OpenCV

[meshtag]

This PR intends to add support for testing dip.corr_2d's output with OpenCV.
All available kernels were used for correlating an image using DIP and OpenCV followed by comparison of their respective outputs.

[zhanghb97]

• I think the test for the Corr2D result belongs to the integration test.
• Can we try to use the GoogleTest framework to verify correctness? Because we are using the GoogleTest framework for other parts according to the previous discussions in our community.
• Currently, the result shows all the cases are different, it's because opencv rounds up, right?

[meshtag]

I was thinking of moving test.h file in tests/ directory instead of tests/UnitTests/ directory so that I can add some functions in it for image processing tests which we are further planning to keep inside tests/IntegrationTests/ directory.
What is your opinion on this? (/cc @zhanghb97 @axmat)

[zhanghb97]

moving test.h file in tests/ directory

What about moving to include/Utils ?

[zhanghb97]

I run the ninja test && ninja image-processing-integration-tests
and got:

17/17 Test #17: FilterTest.OpenCVComparison .............***Failed    0.01 sec

94% tests passed, 1 tests failed out of 17

Total Test time (real) =   0.09 sec

The following tests FAILED:
         17 - FilterTest.OpenCVComparison (Failed)
Errors while running CTest
FAILED: CMakeFiles/test.util 
cd /root/buddy-benchmark/build-check && /usr/bin/ctest --force-new-ctest-process
ninja: build stopped: subcommand failed.