utils: add ostream operator<<() for fragmented_temporary_buffer::view
utils: add ostream operator<<() for fragmented_temporary_buffer::view

We are going to store sstable cells' values in fragmented_temporary_buffers.
This patch will allow checking these values with loggers.

Signed-off-by: Wojciech Mitros <a1165404be25af9d11ad8ab7c126b911264f9b80@scylladb.com>

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