alternator-test: test all attribute types
alternator-test: test all attribute types

Although we planned to initially support only string types, it turns out
for the attributes (*not* the key), we actually support all types already,
including all scalar types (string, number, bool, binary and null) and
more complex types (list, nested document, and sets).

This adds a tests which PutItem's these types and verifies that we can
retrieve them.

Note that this test deals with top-level attributes only. There is no
attempt to modify only a nested attribute (and with the current code,
it wouldn't work).

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

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