Migrate Tethering util functions to CtsTetheringUtils

Bug: 166057846
Bug: 170265597
Test: atest MtsTetheringTest
      atest CtsTetheringTest
Change-Id: I59d529cb50b4b6cdafc6be78ad61a55ee1be0404
3 files changed
tree: 792ebf5fc6b482e79bfaca0747e24a9e1a6cd84c
  1. tests/