sstables: index_reader: Expose access to partition key and tombstone
sstables: index_reader: Expose access to partition key and tombstone

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