test/alternator: verify that nulls are valid inside string and bytes
test/alternator: verify that nulls are valid inside string and bytes

The tests in this patch verify that null characters are valid characters
inside string and bytes (blob) attributes in Alternator. The tests
verify this for both key attributes and non-key attributes (since those
are serialized differently, it's important to check both cases).

The tests pass on both DynamoDB and Alternator - confirming that we
don't have a bug in this area.

Signed-off-by: Nadav Har'El <625169824b719df98706d88646d0aae6f368ae4d@scylladb.com>
Message-Id: <20210824163442.186881-1-625169824b719df98706d88646d0aae6f368ae4d@scylladb.com>

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