Stop speech if other media plays

[rozbb]

Currently, on every platform, if you get a notification while listening to an article, or you start to play something else, the playback will not stop. In the best case, the audio will duck and continue playing, and in the worst case it will appear to be playing from the controls, but no audio will come out. It would nice if RTMS could detect when it lost audio focus and pause playback.

This may be impossible at the moment. The only API that seems to address this is the seemingly defunct Audio Focus API.