Add missing `#include <thread>` in modules/gapi/test/test_precomp.hpp

G-API: ONNX. Const input

* Added const input for ONNX backend

* Returned initMatrixRandu, added some comments, rebase

[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

- migrate GStreamer backed
- migrate FFmpeg backend (with switch on legacy API)
- cv_videoio_capture_retrieve_cb_t uses Mat type instead of number of channels

…ings

- use lazy on-demand initialization

…ization

…_intrinsics

A small clerical error of an author. The correct expression should be "xy += x_*y_;".

…re_write

videoio(plugins): split capture and writer APIs

[G-API] Fix bug of GArray<GArray> passing through a graph

* Add test to check GArray<GArray> passing through a graph (assertion failed)

* G-API: Flatten GArray<T> to std::vector<T> when capturing VCtr

- Also: Fix formatting in garray.hpp

* Refactored test, added valuable check

* Initialize size_t

Co-authored-by: Dmitry Matveev <dmitry.matveev@intel.com>

[GSoC] Added TF and PyTorch segmentation conversion cases

* WIP: Added conversion of segmentation models

* Added tutorial mds

* remove unused

[GSoC] Added TF and PyTorch detection model conversion cases

* Added object detection convertion pipeline and tutorials

* Added tutorial corrections

…ions

HAVE_QT and HAVE_WIN32UI can both be true at the same time
if HAVE_QT, window_w32.cpp is not included in the build, see CMakeLists.txt