[CALCITE-7846] Set operations on one-column table functions can throw or return incorrect rows

[rodrigosetti]

Jira Link

CALCITE-7846

Changes Proposed

Convert one-column Object[] rows from table functions to scalar rows, matching one-column table scans. Add regression coverage for EXCEPT, UNION, and INTERSECT with both operand orders.

The reproducer is:

SELECT n FROM TABLE(numbers_fn())
EXCEPT
SELECT n FROM numbers_table

It now returns n = 1 instead of throwing a ClassCastException.

Testing

• ./gradlew build (passed)