MB-15204 Add PrepareRecovery state to indexer
MB-15204 Add PrepareRecovery state to indexer

Recovery is essentially two step process. Stopping the existing streams
and then restarting. A new state is required so that both phases can be
identified and other system events can be handled differently as per the
phase of recovery.

Change-Id: I03796494c152c84798ddf508d6b6e8cf875f8ba1

jchris/indexing,jchris/indexing,jchris/indexing,jchris/indexing