cassandra_tests: translate tests covering the vector type.

Added cql_vector_test which tests the basic functionalities of the vector type using CQL.
Added vectors_test which tests if descending ordering of vector is supported.

test/cqlpy/cassandra_tests/validation/entities/vectors_test.py

@@ -0,0 +1,16 @@
+# This file was translated from the original Java test from the Apache
+# Cassandra source repository, as of commit 54e46880690bd5effb31116986292c1bdc9e891e
+#
+# The original Apache Cassandra license:
+#
+# SPDX-License-Identifier: Apache-2.0
+
+from ...porting import *
+
+
+def testDescendingOrderingOfVectorIsSupported(cql, test_keyspace):
+    with create_table(cql, test_keyspace, "(k int, v vector<int, 3>, PRIMARY KEY (k, v)) WITH CLUSTERING ORDER BY (v DESC)") as table:
+        execute(cql, table, "INSERT INTO %s(k, v) VALUES (1, [1,2,3])")
+
+        for _ in before_and_after_flush(cql, table):
+            assert_rows(execute(cql, table, "SELECT v FROM %s WHERE k = 1 and v = [1,2,3]"), [[1, 2, 3]])