cql_query_test: add unit test for the more efficient range scan result format
cql_query_test: add unit test for the more efficient range scan result format

The most user-visible aspect of this change is range scans which select
a small subset of the columns. These queries work as the user expects
them to work: unselected columns are not included in determining the
size of the result (or that of the page). This is the aspect this test
is checking for. While at it, also test single partition queries too.

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