ot::NetworkData::Service::DnsSrpAnycastInfo struct

Gets the next DNS/SRP info from the Thread Network Data "DNS/SRP Service Anycast Address" entries. To get the first entry, @p aIterator should be cleared (e.g., a new instance of `Iterator` or calling `Clear()` method).

Finds the preferred DNS/SRP info among all the Thread Network Data "DNS/SRP Service Anycast Address" entries. The preferred entry is determined based on the sequence number value where a larger value (in the sense specified by Serial Number Arithmetic logic in RFC-1982) is considered more recent and therefore preferred.