Getters for LPPresponse

[klagupl]

Hi, I've added these getters to be able to log response in opentelemetry middleware. Example:

		next.ServeHTTP(w, r)
		lppResponse, ok := w.(*agw.LPResponse)
		if ok {
			attrs := semconv.HTTPAttributesFromHTTPStatusCode(lppResponse.Status())
			spanStatus, spanMessage := semconv.SpanStatusFromHTTPStatusCode(lppResponse.Status())
			span.SetAttributes(attrs...)
			span.SetStatus(spanStatus, spanMessage)
		}