transport: result_message: fix the compilation with fmt v5.3.0
transport: result_message: fix the compilation with fmt v5.3.0

Compilation fails with fmt release 5.3.0 when we print a bytes_view
using "{}" formatter.
Compiler's complain is: "error: static assertion failed: mismatch between char-types of context and argument"

Resolve this by explicitly using the operator<<() across the whole
operator<<(std::ostream& os, const result_message::rows& msg) function.

Signed-off-by: Vlad Zolotarov <976c0f8d0852ed6439ad273880b400a75a7c41d0@scylladb.com>
Message-Id: <20190325203628.5902-1-976c0f8d0852ed6439ad273880b400a75a7c41d0@scylladb.com>

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