Port to new API endpoints, revamp output and remove api_endpoint.

[clefru]

Gandi declared https://dns.api.gandi.net end-of-life. The new API endpoints are at api.gandi.net/v5/livedns as documented at https://api.gandi.net/docs/livedns/.

We remove the api_endpoint from the configuration file, as this is not really a user configurable option. We also modernize the output a bit.

[fredericpetit-gh]

Thanks :)

[thouters]

Thanks!