[Alerting] Forking LoTex ruler (#32138)

* updates alerting api to master

* skeleton for lotex ruler

* withPath helper & legacyRulerPrefix const

* forked ruler

* wires up proxy

* safeMacaronWrapper

* working proxy

* jsonExtractor

* lint

pkg/api/response/response.go

@@ -34,7 +34,6 @@ type NormalResponse struct {
 	header     http.Header
 	errMessage string
 	err        error
-	http.ResponseWriter
 }
 
 // Write implements http.ResponseWriter