Add test coverage for setting up initial iptables rules.

Bug: 28362720
Test: bullhead builds, boots
Test: netd_{unit,integration}_test pass
Change-Id: I2ab9269d9bca3a7b8b168b801360d3fdb6119f05
Merged-In: Ifc7b7045f00f7803b31a22d96a04e208917af5a5
4 files changed