Support mDns Known-Answer Suppression

Support the RFC 6762 section 7.1. Known-Answer Suppression.
If the response contains an answer that is also present in the
answer section and the known-answer's TTL is greater than half
of the original TTL, suppress the response.

Bug: 312657709
Test: atest FrameworksNetTests NsdManagerTest
      Passed DUPLICAE SUPPRESSION test case of BCT
Change-Id: I1890e9fba068c1f59a1d93c3514f0e7d07da1814