Merge pull request #17493 from TolyaTalamanov:at/python-bindings-gapi

* Implement G-API python bindings

* Fix hdr_parser

* Drop initlization with brackets using regexp

* Handle bracket initilization another way

* Add test for core operations

* Declaration and definition of View constructor now in different files

* Refactor tests

* Remove combine decorator from tests

* Fix comment to review

* Fix test

* Fix comments to review

* Remove GCompilerArgs implementation from python

Co-authored-by: Pinaev <danil.pinaev@intel.com>

modules/gapi/misc/python/shadow_gapi.hpp

@@ -0,0 +1,7 @@
+#error This is a shadow header file, which is not intended for processing by any compiler. \
+       Only bindings parser should handle this file.
+
+namespace cv
+{
+   GAPI_EXPORTS_W GCompileArgs compile_args(gapi::GKernelPackage pkg);
+} // namespace cv