build: basis of build command

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

commands/root.go

@@ -0,0 +1,21 @@
+package commands
+
+import (
+	"github.com/docker/cli/cli/command"
+	"github.com/spf13/cobra"
+)
+
+func NewRootCmd(dockerCli command.Cli) *cobra.Command {
+	cmd := &cobra.Command{
+		Short: "Build with BuildKit",
+		Use:   "buildx",
+	}
+	addCommands(cmd, dockerCli)
+	return cmd
+}
+
+func addCommands(cmd *cobra.Command, dockerCli command.Cli) {
+	cmd.AddCommand(
+		buildCmd(dockerCli),
+	)
+}