cql3: allow moving data out of raw_value
cql3: allow moving data out of raw_value

in order to be able to elide copying when transferring
data from raw_value.

scylladb/scylla,avikivity/scylla,scylladb/scylla,avikivity/scylla,scylladb/scylla,avikivity/scylla,scylladb/scylla