Better modularization for gnoi_client.go

Better modularization for gnoi_client.go: Untangle gnoi_client.go into separate modules such as config, util, system, file and sonic.

gnoi_client/config/flag.go

@@ -0,0 +1,18 @@
+package config
+
+import (
+	"flag"
+)
+
+var (
+	Module     = flag.String("module", "System", "gNOI Module")
+	Rpc        = flag.String("rpc", "Time", "rpc call in specified module to call")
+	Target     = flag.String("target", "localhost:8080", "Address:port of gNOI Server")
+	Args       = flag.String("jsonin", "", "RPC Arguments in json format")
+	JwtToken   = flag.String("jwt_token", "", "JWT Token if required")
+	TargetName = flag.String("target_name", "hostname.com", "The target name use to verify the hostname returned by TLS handshake")
+)
+
+func ParseFlag() {
+	flag.Parse()
+}

gnoi_client/file/file.go

@@ -0,0 +1,31 @@
+package file
+
+import (
+	"context"
+	"fmt"
+	"encoding/json"
+	pb 	"github.com/openconfig/gnoi/file"
+	"github.com/sonic-net/sonic-gnmi/gnoi_client/utils"
+	"github.com/sonic-net/sonic-gnmi/gnoi_client/config"
+	"google.golang.org/grpc"
+)
+
+func Stat(conn *grpc.ClientConn, ctx context.Context) {
+	fmt.Println("File Stat")
+	ctx = utils.SetUserCreds(ctx)
+	fc := pb.NewFileClient(conn)
+	req := &pb.StatRequest{}
+	err := json.Unmarshal([]byte(*config.Args), req)
+	if err != nil {
+		panic(err.Error())
+	}
+	resp, err := fc.Stat(ctx, req)
+	if err != nil {
+		panic(err.Error())
+	}
+	respstr, err := json.Marshal(resp)
+	if err != nil {
+		panic(err.Error())
+	}
+	fmt.Println(string(respstr))
+}