Add episode change support

[PowerSlime]

On receiving kodik_player_current_episode pause player (already done) and emit socket message. Also implement this method in player.

On receiving changeEpisode from socket player's changeEpisode should be triggered.

Kodik docs

change_episode method. Should be sended by postMessage (player._sendPostMessage method)

{
  method: "change_episode",
  season: 5,
  episode: 3
}

Example: player._sendPostMessage("change_episode", { season: 5, episode: 3 }, false). Should be done like seek method, with possibility to not send socket message.

Requirements:

Method name: changeEpisode
Example: player.methods.changeEpisode({ season, episode })

[PowerSlime]

For more info about socket's endpoints PowerSlime/sync-watch-server#1