expose adData during ad_start event

[Cycymomo]

During ad_start event, the adData Object is available in the player instance

• create a Player

  
  <div id="player"></div>
  <script src="https://api.dmcdn.net/all.js"></script>

const player = DM.player('player', { video: 'x730nnd' })

- attach the listener to it

player.addEventListener('ad_start', () => { console.log(player.adData) })

=> as soon as the ad is displayed, you'll have the `adData` informations in the `player` instance