feat(audio-player): onEnded

[sseppo]

HTML audio-element has onEnded -property to handle things when playing has stopped. Capacitor Audio Player has only isStopped -feature, but that requires to develop a loop that constantly asks if it has ended. Having some event there, or similar onEnded property, would be nice add to the player

[robingenz]

@sseppo Great idea!

@ebarooni Please add a new stop listener to the Audio Player plugin like it's done for the start listener of the Speech Recognition plugin.