Add support for Netcup CloudDNS API Key Authentication

[christianh97]

Welcome

• Yes, I'm using a binary release or the library within the two latest releases.
• Yes, I've searched for similar issues on GitHub and didn't find any.

Detailed Description

Netcup changed the Authentication type from

• Legacy-DNS: Legacy API Key und API-Passwort

to

• CloudDNS: API-Key

The legacy keys are currently used in the plugin, but should be changed in the future because of deprecation.

More information:
https://www.netcup.com/de/helpcenter/dokumentation/domain/unsere-api

Used in NGINXPROXYMANAGER

Effective version of lego

latest

How do you use lego?

Other (please explain)

In which context are you using lego?

Personal use

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• Yes, I have sponsored this project to keep the project stable and maintained.

Confirmation

• Yes, I've included all the information above (version, usage, etc.).

[ldez]

Hello,

The current English version of the Netcup API documentation doesn't contain reference to the new API keys.
I guess they have to sync their documentation.

The API documentation in German is also inconsistent https://www.netcup.com/de/helpcenter/dokumentation/domain/unsere-api#authentifizierung-an-der-api

Based on the technical API documentation, using the legacy API Key or the new API Key is done with the same login endpoint and the same existing apikey attribute.
But it doesn't define required fields, so this is difficult to be sure of that.

I can remove the requirement of password inside lego, but I think I will not create a dedicated option to only set the API key as this element already exists.

Unless this is currently a blocker for users, I would prefer to wait for some clarification of the API usage inside their documentation.