Create a ChangeHookApiListener to listen to the new API Events and
forward these events to the old legacy ChangeHookRunner. This decouples
the hooks and stream events from the internal events. This also
decouples the ChangeHooks interface (and implementations) from all
internal classes except for the new ChangeHookApiListener. This
decoupling should now make it very easy to move all of these classes to
plugins.
Change-Id: I9153dca45727f1c7ea10a8d003e1acf2171b39ac
d432c83a72