adding MediaMetadataRetriever / MediaMetadataReader

Suggest implementing a way to obtain metadata without instantiating a media player
something like https://developer.android.com/reference/android/media/MediaMetadataRetriever

the existing MediaPlayer are just a player, it would be nice to have a separate abstraction for reading metadata, which shall be more lightweight than a full MediaPlayer instance.
it would be useful to build a media playlist for the media player.

https://forum.qt.io/topic/150100/how-to-get-video-s-duration-without-qmediaplayer-but-with-qmediametadata
https://stackoverflow.com/questions/69858215/read-qmediametadata-without-wait-after-set-the-media-source