sstable: add has_scylla_component()
sstable: add has_scylla_component()

has_scylla_component() is going to be used to verify that an sstable has
been generated by a recent version of Scylla. This would make it
possible to reject sstables that may be unsafe to load (e.g. sstables
containing legacy counter shards).

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