Faster ssh user key distribution

[rodecker]

SSH user keys are currently distributed via Ansible, which means they are only updated once every two hours. We'd like to bring this down to minutes.

Possible option would be to use https://jpmens.net/2019/03/02/sshd-and-authorizedkeyscommand/ to check for new keys on Github when a key is not locally available. This would need some rate-limiting to not bombard Github with requests for every login.