Log DNS resolved answers

Introduce a thread-safe queue, DnsQueryLog, to log the DNS resolved answers
which are not found in the cache. The sensitive data is masked in order
not to reveal privacy information. The log can be shown only by
"dumpsys dnsresolver querylog", and it can show only the most-recent-one-hour
queries.

Example output:
DNS query log (last 60 minutes):
  time=17:27:09.262 netId=100 uid=10107 pid=3322 hostname=w*** answer=[2404:***, 216.***] (33ms)
  time=17:27:14.303 netId=100 uid=10097 pid=3363 hostname=w*** answer=[13.***] (21ms)

Bug: 139040977
Test: cd packages/modules/DnsResolver && atest
Test: "adb shell dumpsys dnsresolver querylog" passed
Change-Id: I8d063f4ac920f41c4fbc77e60a3e3a919d9daa62