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 Server Settings -> Cloud Code -> Settings. 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.