Add asynchronous DNS query API

Adds support for asynchronous "raw" DNS API for clients.
API allows apps to use multinetworking capability correctly
and also allows other query types than A/AAAA.

Test: built, flashed, booted
      atest CtsNativeNetDnsTestCases

Change-Id: I43dea2f66523b228975d6e08cba5f9c8ef59d9e5