Merge pull request opencv#21264 from MaximMilashchenko:AudioGStreamer

Audio GStreamer: added support .wav .flac audio formats

* added support .wav, lossless compressed audio formats

* fixed docs

* fixes

* videoio(gstreamer-audio): extra tests, improve error handling

Co-authored-by: Alexander Alekhin <[email protected]>

Author: MaximMilashchenko