add standalone benchmark server

benchmark/server/main.go

@@ -0,0 +1,22 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"math"
+	"time"
+
+	"google.golang.org/grpc/benchmark"
+)
+
+var (
+	duration = flag.Int("duration", math.MaxInt32, "The duration in seconds to run the benchmark server")
+)
+
+func main() {
+	flag.Parse()
+	addr, stopper := benchmark.StartServer()
+	fmt.Println("Server Address: ", addr)
+	<-time.After(time.Duration(*duration) * time.Second)
+	stopper()
+}