Add review information to PullRequest

[Piinks]

Fixes #267

This adds review information to PullRequest. I am gong to be using this to automate a review manager bot.

[robrbecker]

Thanks for putting up a PR! While reviewing I realized that a number of fields are not named in such a way as to map to the correct github field. requestedReviewers will map to requested_reviewers, which is correct. But reviewCommentCount will map to review_comment_count when the name in the response is review_comments. There are other count fields that look to be incorrect as well 😬

So, I'm going to go ahead and merge this, but then follow up with fixes for this and other fields that are wrong. In this case you'd just need something like:

  @JsonKey(name: 'review_comments')
  int? reviewCommentCount;

[robrbecker]

@Piinks give version 8.2.0 a try https://github.com/SpinlockLabs/github.dart/releases/tag/8.2.0

[Piinks]

Sweet! Thank you so much!