New webhook trigger for receiving Pull Request review requests (#24481)

close https://github.com/go-gitea/gitea/issues/16321

Provided a webhook trigger for requesting someone to review the Pull
Request.

Some modifications have been made to the returned `PullRequestPayload`
based on the GitHub webhook settings, including:
- add a description of the current reviewer object as
`RequestedReviewer` .
- setting the action to either **review_requested** or
**review_request_removed** based on the operation.
- adding the `RequestedReviewers` field to the issues_model.PullRequest.
This field will be loaded into the PullRequest through
`LoadRequestedReviewers()` when `ToAPIPullRequest` is called.

After the Pull Request is merged, I will supplement the relevant
documentation.

templates/repo/settings/webhook/settings.tmpl

@@ -238,6 +238,16 @@
 				</div>
 			</div>
 		</div>
+		<!-- Pull Request Review Request -->
+		<div class="seven wide column">
+			<div class="field">
+				<div class="ui checkbox">
+					<input name="pull_request_review_request" type="checkbox" tabindex="0" {{if .Webhook.PullRequestReviewRequest}}checked{{end}}>
+					<label>{{.locale.Tr "repo.settings.event_pull_request_review_request"}}</label>
+					<span class="help">{{.locale.Tr "repo.settings.event_pull_request_review_request_desc"}}</span>
+				</div>
+			</div>
+		</div>
 	</div>
 </div>
 

templates/swagger/v1_json.tmpl

@@ -19934,6 +19934,13 @@
           "type": "string",
           "x-go-name": "PatchURL"
         },
+        "requested_reviewers": {
+          "type": "array",
+          "items": {
+            "$ref": "#/definitions/User"
+          },
+          "x-go-name": "RequestedReviewers"
+        },
         "state": {
           "$ref": "#/definitions/StateType"
         },