This PR adds some unit tests for the `expr::evaluate()` function.
At first I wanted to add the unit tests as part of #11658, but their size grew and grew, until I decided that they deserve their own pull request.
I found a few places where I think it would be better to behave in a different way, but nothing serious.
Closes#11815
* github.com:scylladb/scylladb:
test/boost: move expr_test_utils.hh to .hh and .cc in test/lib
cql3: expr: Add unit tests for bind_variable validation of collections
cql3: expr: Add test for subscripted list and map
cql3: expr: Add test for usertype_constructor
cql3: expr: Add test for tuple_constructor
cql3: expr: Add tests for evaluation of collection constructors
cql3: expr: Add tests for evaluation of column_values and bind_variables
cql3: expr: Add constant evaluation tests
test/boost: Add expr_test_utils.hh
cql3: Add ostream operator for raw_value
cql3: add is_empty_value() to raw_value and raw_value_view
db79f1eb60