Allow transient lists that contain NULL throughout the
evaluation machinery. This makes is possible to evalute things
like `IF col IN (1, 2, NULL)` without hacks, once LWT conditions
are converted to expressions.
A few tests are relaxed to accommodate the new behavior:
- cql_query_test's test_null_and_unset_in_collections is relaxed
to allow `WHERE col IN ?`, with the variable bound to a list
containing NULL; now it's explicitly allowed
- expr_test's evaluate_bind_variable_validates_no_null_in_list was
checking generic lists for NULLs, and was similary relaxed (and
renamed)
- expr_Test's evaluate_bind_variable_validates_null_in_lists_recursively
was similarly relaxed to allow NULLs.
390a0ca47b