Enable mDNS .local resolution

This change implements "5.1 One-Shot multicast DNS Queries"
in RFC 6762 to send standard DNS queries blindly to 224.0.0.251:5353
or [FF02::FB]:5353. mDNS resolution is transparently supported by
calling getaddrinfo() with a hostname ending in "*.local". If the
device exists, getaddrinfo() returns the local addresses. Otherwise,
the query will timeout and return NODATA. This feature doesn't support
reverse-lookups with getnameinfo().

Bug: 140857615
Test: cd packages/modules/DnsResolver && atest
Change-Id: Ie65f220de8c6e5c6e21403ec1f717cf6929023a6