Port G-API demos to API2.0 - background_subtraction_demo/cpp_gapi

[DariaMityagina]

Ticket:

103104

Description:

G-API Background Subtraction Demo, Classification Benchmark C++ G-API Demo, G-API Gaze Estimation Demo and other - fail on NPU with the following error: dynamic shape issues

get_shape was called on a descriptor::Tensor with dynamic shape

• OpenVINO is actively removing API 1.0 from their code
• Both G-API framework and G-API demos use API 1.0 --> which leads to disruption of certain functionality Conclusion: We need to port the G-API demos to API2.0 to make them work.

Affected demos:

• [ ] background_subtraction_demo [ ERROR ] OpenCV(4.8.0-dev) ..\modules\gapi\src\backends\ov\govbackend.cpp:799: error: (-215:Assertion failed) cv::util::holds_alternativecv::GMatDesc(input_meta) in function 'cv::gimpl::ov::PrePostProcWrapper::cfgPreProcessing' - WIP

Also needs the following change to be merge to OpenCV repo:

• [x] https://github.com/opencv/opencv/pull/24938

[DariaMityagina]

This PR should be merged after this one https://github.com/opencv/opencv/pull/24938.