Add depends from highgui to imgcodecs and videoio. And include header from imgcodecs and videoio to imgcodecs

Env setup for testing package implemented using /etc/profile.d;
Variable with path for all native samples added;
Path for test binaries and test data updated.

HAVE_opencv_ocl implies HAVE_OPENCL, so checking for both is not
necessary.

Allow to build samples via OpenCV binaries from distribution package
(find_package with OpenCV_DIR).

2. Modified according to the feedback of the community.

This reverts commit fba72cb6, reversing
changes made to 02131ffb.