Fix panic on DS records by importing dnscontrol rtype package
For record types registered in rtypecontrol.Func, bypass dnsrr.RRtoRC and
call rtypecontrol.NewRecordConfigFromStruct directly, passing the record as
the struct argument. This ensures correct handling of modern rtypes (DS, RP,
etc.) without relying on dnsrr's internal dispatch. Legacy types fall back to
the existing dnsrr.RRtoRC path.
Import _ "github.com/StackExchange/dnscontrol/v4/pkg/rtype" to trigger
init() registration of DS and RP as modern types. Without this import,
dnsrr.RRtoRC would panic with "DS should be handled as modern type".
Pierre-Olivier Mercier
c945ba30ed