[dns-delegated] Some options should be per-domain, not per-component

[Nuru]

In the dns-delegated component, arguments like dns_private_zone_enabled and certificate_authority_enabled should be set individually per domain, instead of per component and shared by all domains (as they currently are) so that public and private domains can be configured in the same component.

In Cloud Posse's convention-over-configuration usage, the reference architecture expect there to be one and only one dns-delegated component and for it to have that name. Having multiple dns-delegated components is not easy to deal with and should not be needed.