Make all player actions Promise based

[nateshmbhat]

Player actions like "stop" , "play" , "pause" , "seekTo" etc , should return a promise so that any actions that needs to be performed synchronously after a previous action can be done properly.

Also sometimes without having a promise based way, multiple actions end up running at a time while the previous one is still being processed by JWPlayer native library and it would cause a crash or some other error.

[nateshmbhat]

Any plan for implementing this? 🙏