Update HTTP status codes to modern codes (#18063)

* 2xx/3xx/4xx/5xx -> http.Status...
* http.StatusFound -> http.StatusTemporaryRedirect
* http.StatusMovedPermanently -> http.StatusPermanentRedirect

modules/web/route_test.go

@@ -67,7 +67,7 @@ func TestRoute2(t *testing.T) {
 				route = 1
 			})
 		}, func(resp http.ResponseWriter, req *http.Request) {
-			resp.WriteHeader(200)
+			resp.WriteHeader(http.StatusOK)
 		})
 
 		r.Group("/issues/{index}", func() {