Move tethering out of ConnectivityService. All client would
use TetheringManager to talk with TetheringService directly.
Bug: 144320246
Test: -build, flash, boot
-atest TetheringTests
Change-Id: Ib051bea724a256f9c4572b566e46ae7b9c4abe6e
Merged-In: Ib051bea724a256f9c4572b566e46ae7b9c4abe6e
Add APEX com.android.tethering.apex for tethering module.
It have tethering apk now and would have jar and library
in follow up CL.
Bug:144320626
Test: build
Change-Id: Ie6158639886e90180dd90347e802a5fe062031b2