Add TetheringCommonTests

Bug: 153614365
Bug: 153613717
Test: atest TetheringTests TetheringCoverageTests
Change-Id: If7c933ec0c72943312cd37bfc66918f10a5504a9
Merged-In: If7c933ec0c72943312cd37bfc66918f10a5504a9
(cherry picked from commit 3d6275df84ebb279e0207b6c1d729bb6d0052856, aosp/1290553)
2 files changed