Use async dns query to resolve all addresses

Currently, it looks like private DNS server resolution uses
OneAddressPerFamilyNetwork and only returns one server address.
It should return all addresses. Use async dns api for this.

Bug: 123435238
Test: atest NetworkStacktests
Change-Id: I9f50da3c8c2e3b12b29bc8844291e4bf1559cd1f
3 files changed