cql3: prevent creation of indexes on non-frozen collections
cql3: prevent creation of indexes on non-frozen collections

Until indexes for non-frozen collections is implemented,
creating such indexes should be disallowed to prevent unnecessary
errors on insertions/selections.

Fixes #3653
Refs #2962
Message-Id: <1e3a38546a333dd9b2506470be778d48c1293868@scylladb.com>

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