ffmpeg: 4.1.3 -> 4.2.1
libvpx: 1.8.0 -> 1.8.1

* Added mechanism to set/toggle NORMAL window to TOPMOST window.

* highgui: remove unnecessary/legacy code

* Adding all possible data type interactions to the perf tests since some
use SIMD acceleration and others do not.

* Disabling full tests by default.

* Giving proper names, removing magic numbers and sanity checks of new
performance tests for the integral function.

* Giving proper names, making array static.

* fix 'chmod' is not recognized as an internal or external command in Windows

https://github.com/opencv/opencv/issues/14939

* cmake: update PCH command handling

* Wrap unsupported by IE layers as custom layers

* Replace pointers to layers blobs to their shapes

* Enable Faster R-CNN with IE backend on CPU

- error: variables in the local address space can only be declared in the outermost scope of a kernel function

* - headers in "infer/" and "infer/ie/" folders are included into gapi_ext_hdrs;
+ because of that a few #includes are required in the headers
- HAVE_INF_ENGINE flag check in headers "infer/ie.hpp" and "infer/ie/util.hpp" is deleted

* - the "ie/util.hpp" header is a private header now as it's used for tests; it's been moved to the scr directory to the place next to the implementation file "ie/giebackend.cpp"
- the path to this header in files "ie/giebackend.cpp" and "test/infer/gapi_infer_ie_test.cpp" is updated
- As it's private header now and explicitly depends on IE, the "HAVE_INF_ENGINE" flag check is returned

   - make static analysis happy

* Support GArray as input in fluid kernels

* Create tests on GArray input in fluid

* Some fixes to fully support GArray

* Refactor code and change the kernel according to review

* Add histogram calculation as a G-API kernel

Add assert that input GArgs in fluid contain at least one GMat

* Convert ImgWarp from SSE SIMD to HAL - 2.8x faster on Power (VSX) and 15% speedup on x86

* Change compile flag from CV_SIMD128 to CV_SIMD128_64F for use of v_float64x2 type

* Changing WarpPerspectiveLine from class functions and dispatching to static functions.

* Re-add dynamic runtime and dispatch execution.

* RRestore SSE4_1 optimizations inside opt_SSE4_1 namespace

* removed private flann documentation
* common tutorial images moved to doc/images
* grouping issues