[FEAT] Add acme.sh DNS alias mode

[Treppengelaender]

Is this a new feature request?

• I have searched the existing issues

Wanted change

Add support for acme.sh's DNS alias mode (--challenge-alias / --domain-alias) via environment variables.

Reason for change

Some setups require delegating the ACME DNS challenge to a separate DNS zone — for example when the primary domain's DNS provider has no API support or you don't want to leave your API Credentials for the Main Domain on a web facing Machine.
Acme.sh already supports this natively, but SWAG doesn't expose it.

Proposed code change

Nope

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[Roxedus]

this image does not use acme.sh