sstableloader: Add support for counter cells
sstableloader: Add support for counter cells

Using magic wormhole cql extensions to send both whole counter
cell and timestamp to scylla server

Message-Id: <07c9a4852207ab1694077839630c0571d3bc652b@scylladb.com>

scylladb/scylla-tools-java,scylladb/scylla-tools-java,scylladb/scylla-tools-java,scylladb/scylla-tools-java