Merge "Move Tether4Key and Tether4Value to common libs" am: 34e16b9537 am: 958d7af11b

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/1978067

Change-Id: If1f4039cfb56d9901658ad9f1f15dc41a5f0f299