feat: make nameservers auto canoncial

[bennetgallein]

Description

the #setNameservers method will accept any input, while powerdns only accept canonical nameservers (ending in .). With the PR, the dot will be automatically appended if it's missing.

Motivation and context

Automatically settings this resolve an issue i'm having with customer not setting the appending dot.

How has this been tested?

tests were fitted

Checklist:

• I have read the CONTRIBUTING document.
• My pull request addresses exactly one patch/feature.
• My pull request contains a title that can be used as a release note.
• I have created a branch for this patch/feature.
• Each individual commit in the pull request is meaningful.
• I have added tests to cover my changes.
• If my change requires a change to the documentation, I have updated it accordingly.

[bennetgallein]

Hey @trizz this might be somewhat controversial on who should do this validation, but since the lib already appends the domain name to records, I think a bit more help for inexperienced administrators is not wrong here. Lmk if there's anything I should change or if you know of any other places that might have this issue.

[trizz]

Hi @bennetgallein ,

Thanks for your PR. I agree that this change makes things a bit more user-friendly and aligns better with the domain name records. I also don’t foresee any breaking changes or backward incompatibility resulting from this change.