Feature request: Return related videos

[superquartet]

Describe the solution you'd like Relating to #17, I would like to obtain the list of videos related to a certain video which are usually displayed at the right side of its watch page. Would it be possible for you to include this feature in your library?

How should this be implemented The results should be returned as a part of class Video like:

final video = await yt.videos.get(videoId);
final List<SearchVideo> relatedVideos = video.relatedVideos;

Or it could be implemented as a new function in the following way if it's more convenient:

final relatedVideos = await yt.search.getRealatedVideos(videoId);