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>

modules/structs/pull_review.go

@@ -36,6 +36,7 @@ type PullReview struct {
 	CommitID          string          `json:"commit_id"`
 	Stale             bool            `json:"stale"`
 	Official          bool            `json:"official"`
+	Dismissed         bool            `json:"dismissed"`
 	CodeCommentsCount int             `json:"comments_count"`
 	// swagger:strfmt date-time
 	Submitted time.Time `json:"submitted_at"`
@@ -92,6 +93,11 @@ type SubmitPullReviewOptions struct {
 	Body  string          `json:"body"`
 }
 
+// DismissPullReviewOptions are options to dismiss a pull review
+type DismissPullReviewOptions struct {
+	Message string `json:"message"`
+}
+
 // PullReviewRequestOptions are options to add or remove pull review requests
 type PullReviewRequestOptions struct {
 	Reviewers     []string `json:"reviewers"`