Add tests for in-kernel VPN/VCN dataplane

This change adds relevant tests for the migrateTun functionality in
NetworkStats.

Bug: 190620024
Test: atest NetworkStatsTest
Original-Change: https://android-review.googlesource.com/1749069
Merged-In: I33f14f2d0f71013a594fd4c8c3914a590d30ea06
Change-Id: I33f14f2d0f71013a594fd4c8c3914a590d30ea06
1 file changed