Replace Hetzner DNS with Cloud and more
Hetzner discontinued their dedicated DNS API in favor of the unified Cloud API. This change replaces the old API with the new one.
Config file syntax had to change to accomodate this as well as the next feature, support for IPv6 prefix changes. This allows to configure a suffix which will then be combined with the dynamic prefix when sent. This way, multiple AAAA records can be updated at once.
Internally, to speed up the transition to the new API, some old design artifacts were removed, but they may come back when other providers (or sufficient mocking and testing) are added.
BREAKING CHANGE: New syntax for config.json.