Implement the exception property on LoadFailed

Created by: Kriste00

Summary

There was recently a new update to lavalink wich adds a new property when loading tracks. The property is named exception, and is present whenever the loadtype is LOAD_FAILED.

Example json

{
  "loadType": "LOAD_FAILED",
  "playlistInfo": {},
  "tracks": [],
  "exception": {
    "message": "The uploader has not made this video available in your country.",
    "severity": "COMMON"
  }
}

I guess just add a property called public TrackLoadException Exception { get; } on LavalinkLoadResult.

Source: https://github.com/Frederikam/Lavalink/pull/174 https://github.com/Frederikam/Lavalink/releases