Added wwctl container exec ... feature

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

@@ -0,0 +1,21 @@
+package child
+
+import "github.com/spf13/cobra"
+
+var (
+	baseCmd = &cobra.Command{
+		Use:    "__child",
+		Hidden: true,
+		RunE:   CobraRunE,
+		Args:   cobra.MinimumNArgs(1),
+	}
+)
+
+func init() {
+
+}
+
+// GetRootCommand returns the root cobra.Command for the application.
+func GetCommand() *cobra.Command {
+	return baseCmd
+}