Pass ConfigOptions to scalar UDFs via FFI

[timsaucer]

Which issue does this PR close?

• Closes Support passing ConfigOptions to scalar functions via FFI #17035

Rationale for this change

Now that we have proper FFI_ConfigOptions we can pass these to scalar UDFs via FFI.

What changes are included in this PR?

Instead of passing default options, pass in converted config options from the input.

Also did a drive by cleanup of switching to using FFI_ColumnarValue since it is now available.

Are these changes tested?

Unit test added.

Are there any user-facing changes?

This is a breaking API change, but not one that users will interact with directly. It breaks the ABI for FFI libraries, which is currently unstable.

[Copilot]

Pull request overview

This PR enables passing ConfigOptions to scalar UDFs via the FFI (Foreign Function Interface), resolving issue #17035. The changes allow external FFI libraries to access session configuration options when executing scalar functions, which was previously blocked by the TODO comment about passing config options.

Changes:

• Added config_options parameter to FFI scalar UDF invocation signature
• Switched from returning WrappedArray to FFI_ColumnarValue for better scalar/array handling
• Added comprehensive test validating config option passing through FFI boundary

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
datafusion/ffi/tests/ffi_udf.rs	Added test test_config_on_scalar_udf validating that config options (specifically timezone) are correctly passed to FFI UDFs
datafusion/ffi/src/udf/mod.rs	Updated FFI scalar UDF signatures to include config_options parameter, converted between FFI and native ConfigOptions, switched to FFI_ColumnarValue return type
datafusion/ffi/src/tests/udf_udaf_udwf.rs	Implemented TimeZoneUDF test helper that returns the configured timezone
datafusion/ffi/src/tests/mod.rs	Added create_timezone_udf function to the foreign library module exports

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[timsaucer]

@alamb Asking for your review since you put up the issue, but I can try to find someone who's spent more time on the FFI code if you like

[davisp]

+1

It's a straightforward addition now that FFI_ConfigOptions exists.