The config is currently unused in some classes, but this is okay since
it might be used in the future.
Change-Id: Ie25fc52cc5d3476c9445e182975d229991316bd3
For logged out users we store their test state and an anonymous
identifier in local storage. So long as the test is enabled, we include
these in any logging that occurs.
This is done entirely client-side, to avoid any cache issues caused by
state depending on cookies from PHP for logged out users.
Bug: T291307
Change-Id: Ib39e2f2146cdfdac9df5690ee3de75718f0f2731