Unify dns handling in P2P diffusion

[coot]

trafficstars

Diffusion.P2P.Interfaces take two dns related entries:

• diNtnDomainResolver :: [DomainAddress] -> m (Map DomainAddress (Set ntnAddr)),
• diDnsActions :: DNSActions resolver resolverError m.

It would be preferable to just use 'DNSActions' instead.