when bidirectional replication is set up.
If ReplicaModifications is enabled in the replication
configuration, sync metadata updates to source if
replication rules are met. By default, if this
configuration is unset, MinIO automatically sync's
metadata updates on replica back to the source.
Delete marker replication is implemented for V2
configuration specified in AWS spec (though AWS
allows it only in the V1 configuration).
This PR also brings in a MinIO only extension of
replicating permanent deletes, i.e. deletes specifying
version id are replicated to target cluster.
