Render Frame NV12 on CPU
* render frame on CPU
* doxygen fix
* address review from Alexey
* comment fixes
* Address comments from Ruslan
* remove NV12 specific
* mat clone and more renaming
* misprint fix
* G-API: Addressed various documentation issues
- Fixed various typos and missing references;
- Added brief documentaion on G_TYPED_KERNEL and G_COMPOUND_KERNEL macros;
- Briefly described GComputationT<>;
- Briefly described G-API data objects (in a group section).
* G-API: Some clean-ups in doxygen, also a chapter on Render API
* G-API: Expose more graph compilation arguments in the documentation
* G-API: Address documentation review comments
G-API: Parameterized render tests (#14892)
* Init commit
* Add mat size as test parameter
* Add test for text render
* Add test for rect render
* Add tests for line and circle
* Remove old render tests
* Init output mats
* Remove methods input arguments
* Add comment about data loss in BGR2NV12 conversion
* Add edge test cases
* Replace default color for out mats black -> white
