Add dismiss review feature (#12674)

* Add dismiss review feature

refs:
    https://github.blog/2016-10-12-dismissing-reviews-on-pull-requests/
    https://developer.github.com/v3/pulls/reviews/#dismiss-a-review-for-a-pull-request

* change modal ui and error message

* Add unDismissReview api

Signed-off-by: a1012112796 <1012112796@qq.com>
Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: 6543 <6543@obermui.de>

services/pull/review.go

@@ -253,3 +253,54 @@ func SubmitReview(doer *models.User, gitRepo *git.Repository, issue *models.Issu
 
 	return review, comm, nil
 }
+
+// DismissReview dismissing stale review by repo admin
+func DismissReview(reviewID int64, message string, doer *models.User, isDismiss bool) (comment *models.Comment, err error) {
+	review, err := models.GetReviewByID(reviewID)
+	if err != nil {
+		return
+	}
+
+	if review.Type != models.ReviewTypeApprove && review.Type != models.ReviewTypeReject {
+		return nil, fmt.Errorf("not need to dismiss this review because it's type is not Approve or change request")
+	}
+
+	if err = models.DismissReview(review, isDismiss); err != nil {
+		return
+	}
+
+	if !isDismiss {
+		return nil, nil
+	}
+
+	// load data for notify
+	if err = review.LoadAttributes(); err != nil {
+		return
+	}
+	if err = review.Issue.LoadPullRequest(); err != nil {
+		return
+	}
+	if err = review.Issue.LoadAttributes(); err != nil {
+		return
+	}
+
+	comment, err = models.CreateComment(&models.CreateCommentOptions{
+		Doer:     doer,
+		Content:  message,
+		Type:     models.CommentTypeDismissReview,
+		ReviewID: review.ID,
+		Issue:    review.Issue,
+		Repo:     review.Issue.Repo,
+	})
+	if err != nil {
+		return
+	}
+
+	comment.Review = review
+	comment.Poster = doer
+	comment.Issue = review.Issue
+
+	notification.NotifyPullRevieweDismiss(doer, review, comment)
+
+	return
+}