Add dns_adb_createaddrinfosfind() for address-based lookups

Add dns_adb_createaddrinfosfind() for address-based lookups

Add a new ADB API function that creates a find from a list of addresses
rather than by looking up nameserver names.  This enables the resolver
to handle address-based delegations (NS-based with glues or DELEG with
addresses) and name-based delegations uniformly (i.e. the list of finds
from ADB is handled the same way no matter the type of the delegation).