Revert "removed unused container child"

This reverts commit 30bc445a89.

internal/app/wwctl/container/exec/child/root.go

@@ -0,0 +1,24 @@
+package child
+
+import "github.com/spf13/cobra"
+
+var (
+	baseCmd = &cobra.Command{
+		DisableFlagsInUseLine: true,
+		Use:                "__child",
+		Hidden:             true,
+		RunE:               CobraRunE,
+		Args:               cobra.MinimumNArgs(1),
+		FParseErrWhitelist: cobra.FParseErrWhitelist{UnknownFlags: true},
+	}
+	binds []string
+)
+
+func init() {
+	baseCmd.PersistentFlags().StringArrayVarP(&binds, "bind", "b", []string{}, "bind points")
+}
+
+// GetRootCommand returns the root cobra.Command for the application.
+func GetCommand() *cobra.Command {
+	return baseCmd
+}