SystemHealth: Tests defining token caching behavior.

This will define the behavior for both customToken=false and custom=true
authenticators.

An upside of this change is that a lot of assumed token behavior vis a
vis android:customToken=true authenticators that was never tested now is
tested.

Bug: 21530782

Change-Id: I4a1aa52a9ecf5cd129c557e8e26839be11019d84
7 files changed