HLSProvider/JW5-JW6 - report live playlist accurately

only report position/duration/buffer for VOD playlist and live playlist with duration > 60s.
=> jw will report playlist as being live correctly.
=> user can still seek in DVR playlist (live with duration > 60s)
fix https://github.com/mangui/HLSprovider/issues/69 for jw5-jw6