This patch adds many tests verifying the behavior of WRITETIME() and
TTL() on individual elements of maps, sets and UDTs, serving as a
regression test for issue #15427. We also add tests verifying our
understanding of related issues like WRITETIME() and TTL() of entire
collections and of individual elements of *frozen* collections.
All new tests pass on Cassandra 5.0, helping to verify that our
implementation is compatible with Cassandra. They also pass on
ScyllaDB after the previous patch (most didn't before that patch).
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
