cudacodec::VideoReader: allow frame seek on initialization

[cudawarped]

Allow seeking of video source on initialization of cudacodec::VideoReader when new variable VideoReaderInitParams::iFirstFrame != 0.

Dependant on opencv/opencv#24012

Fixes #3541.

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See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

• I agree to contribute to the project under Apache 2 License.
• To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
• The PR is proposed to the proper branch
• There is a reference to the original bug report and related work
• There is accuracy test, performance test and test data in opencv_extra repository, if applicable
  Patch to opencv_extra has the same branch name.
• The feature is well documented and sample code can be built with the project CMake

[cudawarped]

[ RUN      ] CUDA_Codec/Seek.Reader/0, where GetParam() = Quadro P2000
unknown file: Failure
C++ exception with description "OpenCV(4.8.0-dev) /home/ci/opencv_contrib/modules/cudacodec/src/video_reader.cpp:198: error: (-215:Assertion failed) skipFrame() in function 'VideoReaderImpl'
" thrown in the test body.
[  FAILED  ] CUDA_Codec/Seek.Reader/0, where GetParam() = Quadro P2000 (217 ms)

@asmorkalov Sorry I forgot to mention that this is dependant on opencv/opencv#24012. In addition I've just realized it won't work on windows so I've added build guards to remove the test until the FFmpeg windows wrapper is updated.

[cudawarped]

[----------] 1 test from CUDA_Codec/Seek
[ RUN ] CUDA_Codec/Seek.Reader/0, where GetParam() = Quadro P2000
/home/ci/opencv_contrib/modules/cudacodec/test/test_video.cpp:638: Failure
Expected equality of these values:
iFrame
Which is: 19
static_cast(firstFrameIdx)
Which is: 18
[ FAILED ] CUDA_Codec/Seek.Reader/0, where GetParam() = Quadro P2000 (98 ms)
[----------] 1 test from CUDA_Codec/Seek (98 ms total)

@asmorkalov Fixed.

[asmorkalov]

👍