scylla-sstable: add ability to dump optionals and utils::UUID
scylla-sstable: add ability to dump optionals and utils::UUID

Needed for the ME sstable format.

Signed-off-by: Michael Livshin <ae60993c65de9cdf2ca07b7426c976808535d555@scylladb.com>

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