Make resolver timeout configurable via setResolverConfiguration()

This is infrastructure for tests simulating unresponsive nameservers.
With the default timeout of 5 seconds, with 4 retries per lookup, makes
this sort of tests impractical.

Change-Id: I2a2315507a4725744de6caa46121d83af13b59d1
Test: netd_unit_test --gtest_filter='ResolverTest.*'
5 files changed