feat: add dfbench cmd

Signed-off-by: Gaius <gaius.qi@gmail.com>

cmd/dfbench/cmd/dragonfly.go

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package dfbench
+package cmd
 
 import (
 	"context"

cmd/dfbench/cmd/nydus.go

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package dfbench
+package cmd
 
 import (
 	"context"

cmd/dfbench/cmd/root.go

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package dfbench
+package cmd
 
 import (
 	"os"

cmd/dfbench/main.go

@@ -16,8 +16,10 @@
 
 package main
 
-import "github.com/dragonflyoss/perf-tests/cmd/dfbench"
+import (
+	"github.com/dragonflyoss/perf-tests/cmd/dfbench/cmd"
+)
 
 func main() {
-	dfbench.Execute()
+	cmd.Execute()
 }