Add write check for creating Commit status (#20332)

- Add write code checks for creating new commit status
- Regression #5314

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

routers/api/v1/api.go

@@ -1017,7 +1017,7 @@ func Routes() *web.Route {
 				}, mustAllowPulls, reqRepoReader(unit.TypeCode), context.ReferencesGitRepo())
 				m.Group("/statuses", func() {
 					m.Combo("/{sha}").Get(repo.GetCommitStatuses).
-						Post(reqToken(), bind(api.CreateStatusOption{}), repo.NewCommitStatus)
+						Post(reqToken(), reqRepoWriter(unit.TypeCode), bind(api.CreateStatusOption{}), repo.NewCommitStatus)
 				}, reqRepoReader(unit.TypeCode))
 				m.Group("/commits", func() {
 					m.Get("", context.ReferencesGitRepo(), repo.GetAllCommits)