test: add sqllogictest coverage for UDWF return types in information_…

[karuppuchamysuresh]

What changes were proposed in this pull request?

Add sqllogictest coverage to verify that information_schema.routines correctly reports return types for window user-defined functions (UDWFs).

Why are the changes needed?

PR #20079 updated the information schema to use newer APIs for reporting function return types. Previously, window functions always showed NULL for their return type in information_schema.routines. The implementation was fixed but
lacked test coverage to prevent regression.

This PR adds tests specifically for the get_udwf_args_and_return_types code path in datafusion/catalog/src/information_schema.rs.

Which issue does this PR close?

Closes #20090

What tests are included?

This PR adds 6 test cases to datafusion/sqllogictest/test_files/information_schema.slt:

1. Test window functions with concrete return types:

   • row_number → Int64
   • rank → Int64
   • dense_rank → Int64

2. Test window functions with generic return types:

   • lag → Null (type depends on input)
   • lead → Null (type depends on input)

3. Combined test:

   • Verifies multiple window functions together
   • Checks is_deterministic flag
   • Tests ordering of results

Before this PR (current behavior):

All window functions show NULL for data_type:

+--------------+-----------+---------------+
| routine_name | data_type | function_type |
+--------------+-----------+---------------+
| row_number | NULL | WINDOW |
| rank | NULL | WINDOW |
| dense_rank | NULL | WINDOW |
+--------------+-----------+---------------+

After PR #20079 merges (expected behavior):

Window functions will show proper return types:

+--------------+-----------+---------------+
| routine_name | data_type | function_type |
+--------------+-----------+---------------+
| row_number | Int64 | WINDOW |
| rank | Int64 | WINDOW |
| dense_rank | Int64 | WINDOW |
+--------------+-----------+---------------+

Dependencies

⚠️ This PR depends on #20079

The tests in this PR will fail until #20079 is merged because the underlying implementation doesn't yet report window function return types correctly. Once #20079 merges, these tests will pass and ensure the fix works correctly.

Are there any user-facing changes?

No, this only adds test coverage. The functionality change is in PR #20079.

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📝 Initial Comment (Add After Creating PR)

Status

This PR is marked as Draft because it depends on #20079 being merged first.

Current test status:

• ✅ All test syntax is correct
• ⚠️ Tests currently fail (expected - they detect the bug that Use return_field_from_args in information schema and date_trunc #20079 fixes)
• ✅ Tests will pass once Use return_field_from_args in information schema and date_trunc #20079 merges

Verification:

I've manually verified the current behavior:

select routine_name, data_type, function_type                                                                                                                                                                                                 
from information_schema.routines                                                                                                                                                                                                              
where routine_name = 'row_number';                                                                                                                                                                                                            
                                                                                                                                                                                                                                              
Current result: row_number | NULL | WINDOW                                                                                                                                                                                                    
Expected after #20079: row_number | Int64 | WINDOW                                                                                                                                                                                            
                                                                                                                                                                                                                                              
This PR will be ready for review as soon as #20079 is merged.