Tethering apex module is renmae from com.android.tethering.aepx to com.android.tethering. Renmae tethering apex file context accordingly. Also add filegroup for tethering apex. Bug: 146471733 Test: build, flash, boot atest TetheringTests atest CtsTetheringTest Change-Id: I41ec17604067c684123085841182408c4e315ec2