G-API planar kernels (#14917)

* Added resizeP with tests

* NV12 planar filters

* fix warnings in ResizeP test

* fix out mat ocv warning

* sz_on - > sz rename

* cpu tests new signature

* try to fix resizeP test

* trailing spaces remove

* doxygen doc fixed

* doxygen minor fix

* more doxygen fixes

* Doxygen corrected and extended after review.

Changed quotes to brackets when including public includes (#14741)

G-API: Implement color-convert kernels (#14513)

* Implement color-convert kernels

* Fix rgb2yuv422 reference version

* Fix comments to review

* Restore NV12toBGR in imgproc.hpp

* Add accuracy tests

* Fix doxygen

* Fix ref version yuv422

* Fix warnings

* Fix typos

* Fix simd version yuv422

* Fix warnings

* Fix compile error

* Fix warning

* Remove comment

* Add Sobel kernel which returns both dx and dy

* Splice dx and dy and extend add_border function

Also change some tests parameters

* Add borderValue parameter in test

* Introduces fluid kernel for sobelxy

Adds tests (basic and performance) on new backend

* Introduces BufHelper struct for some arithmetic

* Renamed Sobel operator GAPI kernel to match with OpenCV naming rules

* Fixed perf tests

* Small refactoring to check CI issue

* Refactored alignment for kernel wrappers in imgproc.hpp

* Update G-API code base to 27-Sep-18

Changes mostly improve standalone build support

* G-API code base update 28-09-2018

* Windows/Documentation warnings should be fixed
* Fixed stability issues in Fluid backend
* Fixed precompiled headers issues in G-API source files

* G-API code base update 28-09-18 EOD

* Fixed several static analysis issues
* Fixed issues found when G-API is built in a standalone mode

* G-API Initial code upload

* Update G-API code base to Sep-24-2018

* The majority of OpenCV buildbot problems was addressed

* Update G-API code base to 24-Sep-18 EOD

* G-API code base update 25-Sep-2018

* Linux warnings should be resolved
* Documentation build should become green
* Number of Windows warnings should be reduced

* Update G-API code base to 25-Sep-18 EOD

* ARMv7 build issue should be resolved
* ADE is bumped to latest version and should fix Clang builds for macOS/iOS
* Remaining Windows warnings should be resolved
* New Linux32 / ARMv7 warnings should be resolved

* G-API code base update 25-Sep-2018-EOD2

* Final Windows warnings should be resolved now

* G-API code base update 26-Sep-2018

* Fixed issues with precompiled headers in module and its tests