Add test cases in resolv_unit_test for proto NetworkDnsEventReported verification

1. Add resolv_stats_test_utils for testing resolv stats
2. Add proto verification in resolv_unit_test
3. Add the test case for verifying the correctness for
   fromNetworkDnsEventReportedStr and matchers.

Bug: 119862317
Test: atest
Change-Id: I1c7ad82e4766c6f34ef8104d91460e0811c58b60