Add API routes to lock and unlock issues (#34165)

This pull request adds a GitHub-compatible API endpoint to lock and
unlock an issue.

The following routes exist now:
- `PUT /api/v1/repos/{owner}/{repo}/issues/{id}/lock` to lock an issue
- `DELETE /api/v1/repos/{owner}/{repo}/issues/{id}/lock` to unlock an issue

Fixes #33677
Fixes #20012

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

modules/structs/issue.go

@@ -266,3 +266,8 @@ type IssueMeta struct {
 	Owner string `json:"owner"`
 	Name  string `json:"repo"`
 }
+
+// LockIssueOption options to lock an issue
+type LockIssueOption struct {
+	Reason string `json:"lock_reason"`
+}