Cloud9 is an browser based IDE. It runs on an EC2 instance in your account, so you are paying for it. The good message is, that is will stop after 1/2 hour of inactivity. It has the main languages preinstalled, so you do not have to install go.
Cloud9in your AWS service search bar. The layout will change over time:
You have to setup git for yourself. There is no standard backup of your EBS Volumes, so save early, safe often to prevent data loss.
You could also use the free CloudShell of AWS. It provides you with 10G of free storage, but you have to reinstall GO each time you start the shell. If you just add the line:
sudo yum -y install go
.bashrc this will automatically done at startup.
Also as this is a text based terminal, you would have to use VI/VIM as an editor.