[#1437] neofs-cli: Move util command to a separate package

Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>

cmd/neofs-cli/modules/util/sign.go

@@ -0,0 +1,22 @@
+package util
+
+import (
+	"github.com/spf13/cobra"
+)
+
+const (
+	signFromFlag = "from"
+	signToFlag   = "to"
+)
+
+var signCmd = &cobra.Command{
+	Use:   "sign",
+	Short: "Sign NeoFS structure",
+}
+
+func initSignCmd() {
+	signCmd.AddCommand(signBearerCmd, signSessionCmd)
+
+	initSignBearerCmd()
+	initSignSessionCmd()
+}