Add review request api (#11355)

* Add review request api

* add : POST /repos/{owner}/{repo}/pulls/{index}/requested_reviewers
* Remove : DELET /repos/{owner}/{repo}/pulls/{index}/requested_reviewers
* fix some request review bug
* block delet request review by models/DeleteReview()

Signed-off-by: a1012112796 <1012112796@qq.com>

* make fmt

* fix bug

* fix test code

* fix typo

* Apply suggestion from code review @jonasfranz

* fix swagger ref

* fix typo

Co-authored-by: Lauris BH <lauris@nix.lv>

* fix comment

* Change response message

* chang response so some simplfy

* Add ErrIllLegalReviewRequest
fix some nits

* make fmt

* Apply suggestions from code review

Co-authored-by: silverwind <me@silverwind.io>

* * Add team support
* fix test
* fix an known bug

* fix nit

* fix test

* Apply suggestions from code review

Co-authored-by: zeripath <art27@cantab.net>

* update get api and add test

Co-authored-by: Lauris BH <lauris@nix.lv>
Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: zeripath <art27@cantab.net>

modules/structs/pull_review.go

@@ -30,6 +30,7 @@ const (
 type PullReview struct {
 	ID                int64           `json:"id"`
 	Reviewer          *User           `json:"user"`
+	ReviewerTeam      *Team           `json:"team"`
 	State             ReviewStateType `json:"state"`
 	Body              string          `json:"body"`
 	CommitID          string          `json:"commit_id"`
@@ -90,3 +91,9 @@ type SubmitPullReviewOptions struct {
 	Event ReviewStateType `json:"event"`
 	Body  string          `json:"body"`
 }
+
+// PullReviewRequestOptions are options to add or remove pull review requests
+type PullReviewRequestOptions struct {
+	Reviewers     []string `json:"reviewers"`
+	TeamReviewers []string `json:"team_reviewers"`
+}