support shuffle on/off intent

[hyzhak]

on

shuffle, shuffle on, shuffle the music, shuffle mode

Lets the user request that the skill turn on a shuffle mode, usually for audio skills that stream a playlist of tracks.
For skills that stream audio using the AudioPlayer interface, users can invoke this intent without using your invocation name if your skill is currently playing audio or was the most recent skill to play audio. The intent is sent to your skill in this case even if AMAZON.ShuffleOnIntent is not in your intent schema.

off

stop shuffling, shuffle off, turn off shuffle

Lets the user request that the skill turn of a shuffle mode, usually for audio skills that stream a playlist of tracks.
For skills that stream audio using the AudioPlayer interface, users can invoke this intent without using your invocation name if your skill is currently playing audio or was the most recent skill to play audio. The intent is sent to your skill in this case even if AMAZON.ShuffleOffIntent is not in your intent schema.