[coverage] Conformance findings: STATEMENT-023 #885

Surfaced by the multi-language coverage fan-out while conformance-testing these SPEC-IDs against databricks/databricks-sql-python.

Each is committed as an expected-failure (xfail) test in the coverage PR — the test asserts the CORRECT behavior and stays red until this driver is fixed.

• STATEMENT-023: cursor.rowcount returns the -1 unknown/NA sentinel for DDL (CREATE TABLE) and SELECT instead of normalizing to 0; it is initialised to -1 and only overwritten when the server reports numModifiedRows, which is None for those statements

Reference driver PR: databricks/databricks-sql-go#416
Coverage PR (reproducing xfail tests): https://github.com/databricks/databricks-driver-test/pull/1010