Fix TetheredClient and TetheredClientTest

 - Ensure that addAddresses preserves the ordering of addresses
 - Fix assertion that was supposed to check equality of TetheredClient
   with a different tethering type, and used the same type.

Bug: 148996181
Test: atest TetheringTests
Change-Id: I86cef7b834d7ae7afa3d1d748ccac6b3a7e57ebc