[G-API]: Performance tests for kmeans
* - Perf.Tests for kmeans(2D, 3D (Point2f/3f), ND (Mat))
- New file for common parts of acc. and perf. tests for core kernels added
- Some typos corrections
* Applying comments
[G-API]: Performance tests for fitLine and findContours
* Perf.Test for findContours(H)
* Perf.Test for fitLine(2D.3D;Mat,vector<Point2i/2f/2d/3i/3f/3d>)
* Reducing the template specializations number
* Applying comments
[G-API]: Performance tests for boundingRect
* Update boundingRect() tests with the changes from fitLine() PR
* Add performance tests for boundingRect
* Applying comment about g_type_of_t
* Addressing comments
* Addressing comment: replace cmp_f by CompareF in perf.tests + add the default constructor for CompareF
* Fix typo
