We have launched in our dashboard a place where you can select and upload your cloud code files through the web browser. To find this feature, you have to access dashboard.back4app.com, select your app, click on Features -> Cloud Code -> Server. There you will find a file explorer through which you can manage your files and folders, an upload button and also a place where you can see your files.
Command Line tool is available for Back4app. Click here to know more.