restructure runtime code

pkg/runtime/command.go

@@ -0,0 +1,19 @@
+package runtime
+
+import (
+	"github.com/micro/cli/v2"
+)
+
+// Command adds micro runtime commands to the cli app
+func Command(app *cli.App) *cli.Command {
+	command := cli.Command{
+		Name:        "micro",
+		Description: "starts the go-micro runtime services",
+		Category:    "Micro",
+		Action: func(c *cli.Context) error {
+			runtime := New()
+			return runtime.Start()
+		},
+	}
+	return &command
+}