[replication] Support ICVs in a master-master setup

Currently an ICV ends up as a Put in the HLogs, which ReplicationSource ships to ReplicationSink that in turn only recreates the Put and not the ICV itself. This means that in a master-master replication setup where the same counters are implemented on both side, the Puts will actually overwrite each other.

We need to find a way to support this use case.