sstables: add output operator for sstable run
sstables: add output operator for sstable run

the output will look like as follow:

Run = {
	Identifier: 647044fd-d3d4-43c4-b014-b546943ead0d
	Fragments = {
		1471=-9223317893235177836:-7063220874380325121
		1478=5924386327138804918:8070482595977135657
		1472=-7063202587832032132:-4903425074566642766
		1473=-4903298949436784325:-2739716797579745183
		1474=-2739703419744073436:-589328117804966275
		1477=3734534455848060136:5924372906965333873
		1476=1579822226461317527:3734518878340722529
		1475=-589322393539097068:1579813857236466583
		1479=8070499046054048682:9223317594733741806
	}
}

Signed-off-by: Raphael S. Carvalho <1e2942cea40e3b4d2162dfcd9e53e41c05a84d22@scylladb.com>
Message-Id: <20190524043331.5093-1-1e2942cea40e3b4d2162dfcd9e53e41c05a84d22@scylladb.com>

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