because with the current implementation the audio needs to be preload and at least be played one time to get
the audio id which is needed to get the audio duration with the current getDuration API.
I've describes the problem in detail here:
https://discuss.cocos2d-x.org/t/audioengine-interface-improvement/34034
* remove “experimental” in audio dir
* update audio bindings
* fix "{" match error
* no need "experimental" for thread pool
* remove both out-of-date js api files
* Avoids crashes on some specific android devices (e.g. Red Mi Note4) while decoding audio file in multi-threads.
* Improves performance of decoding, 2x faster