Add sqllogictest coverage for UDWF return types in information_schema

[AndreaBozzo]

Context

In #20079, the information_schema was updated to use return_field_from_args / return_field / WindowUDFFieldArgs::field instead of the older return_type API for UDFs, UDAFs, and UDWFs.

As noted in this review comment, it would be good to add sqllogictest coverage to verify that information_schema.routines correctly reports return types for window UDFs (the get_udwf_args_and_return_types path).

What needs to be done

Add a sqllogictest (in test_files/information_schema.slt or a new file) that:

1. Registers a window UDF (or uses a built-in one)
2. Queries information_schema.routines filtering for that window function
3. Asserts the return type column is populated correctly (previously it was always NULL)

The relevant code is in datafusion/catalog/src/information_schema.rs around the get_udwf_args_and_return_types function.

Willingness to submit a PR

Yes, but as this can potentially be a good newcomer task i'm up to leave for someone else

[karuppuchamysuresh]

I'd like to work on this issue. I'll wait for #20079 to merge and then submit a PR with sqllogictest coverage for UDWF return types in information_schema. Thanks!