inwx: Modernize record conversion

[TomOnTime]

Dear @patschi. I could use your help. I'm doing upgrades to the code base and I have no way to test your provider. Please run the integration test and let me know the result. How to run integration tests is here: https://docs.dnscontrol.org/developer-info/integration-tests

Summary

• replace legacy record construction with current domain-aware factories
• replace the combined legacy getter with typed RDATA output
• preserve INWX target-dot and split-priority behavior

Validation

• ../../bin/is_modern.sh (Steps 1-7 clean)
• go test ./providers/inwx
• bin/generate-all.sh
• go test ./...

[patschi]

Sure! I thought about adding INWX to automated testing, and read the docs for it - but wasn't motivated enough to create a free account on some page to send credentials and unsure about the email address to mail it to...

Can I send you the credentials (packed in a Bitwarden Send link) via email? I have your email address.

Also: Would you want me/us to use their sandbox environment, or their production one with real domain? If sandbox, my personal account or dedicated account?

[TomOnTime]

Hey there! Good to hear from you!

Sure! I thought about adding INWX to automated testing, and read the docs for it - but wasn't motivated enough to create a free account on some page to send credentials and unsure about the email address to mail it to...

Can I send you the credentials (packed in a Bitwarden Send link) via email? I have your email address.

Yeah, send them any way that works for you! I'm flexible!

Also: Would you want me/us to use their sandbox environment, or their production one with real domain? If sandbox, my personal account or dedicated account?

sandbox vs production: whatever is cheapest. however, if the sandbox is significantly slower than production I may change my answer LOL. I prefer that the integration tests can run in 5-6 minutes. (Every now and then I find the 2-3 slowest and beat them up a bit)

personal or dedicated account: I prefer a dedicated account. I don't mind an API key to a personal account if its locked down so I can't accidentally ruin your other domains. Whatever you're comfortable with.

Thanks!
Tom

[TomOnTime]

Is the PR ready to be merged?