Provides a class that initiates AB-test bucketing and registers
as a MF module. Activates the reading depth test for users who are bucketed
in either buckets "A" or "B".
Does not add event-logging or visual style changes for page issues AB test.
Bug: T193584
Change-Id: If8504a35059c6d1b056cef063a595b1c2ffd351a
Use local imports instead given all relevant files are within the
same repository, and don't vary by configuraion.
Bug: T140807
Depends-On: If3edac9a35b346af0320c12f70c0d978a6346201
Change-Id: Ife3cc345a63aff452e93accbe0a593fbaa358732
