ns1: Implement EnsureDomainExists (#1157)
ns1: Implement EnsureDomainExists (#1157)

API support is there, let's use it.

Co-authored-by: Tom Limoncelli <99731c54e56da7667c48f35af95dff25592e8fcf@stackoverflow.com>
StackExchange/dnscontrol,StackExchange/dnscontrol,StackExchange/dnscontrol