Add the new dumpstate listener methods to implementations

Add dummy implementations for status, error and finished callbacks.
Next step: wire these up end-to-end; change Shell's listener to be
BugreportManager.BugreportListener, and make it communicate with the
native service explicitly through the new system api.

BUG: 111441001
Test: Verified progress in interactive bugreport still works
Change-Id: Iad0bb7b23b04f6bc7e3b31e5071df42409c78684