feat(udf): introduce `#[derive(StructType)]` for struct types in Rust UDF #15372

4 / 8 tasks completed

4 tasks still to be completed

Task	Status
I have written necessary rustdoc comments	Completed
I have added necessary unit tests and integration tests	Completed
I have added test labels as necessary. See details.	Incomplete
I have added fuzzing tests or opened an issue to track them. (Optional, recommended for new SQL features #7934).	Incomplete
My PR contains breaking changes. (If it deprecates some features, please create a tracking issue to remove them in the future).	Incomplete
All checks passed in `./risedev check` (or alias, `./risedev c`)	Completed
My PR contains critical fixes that are necessary to be merged into the latest release. (Please check out the details)	Incomplete
My PR needs documentation updates. (Please use the Release note section below to summarize the impact on users)	Completed
For non-struct return types, I suppose there should be no change on both syntax and implementation.	Incomplete
For struct return types, can we identify these cases based on an unrecognized return type of the function (other than well-known types like `i32` or `bool`)?	Incomplete
if the return type is a struct, they have to write `#[function]` by themselves.	Incomplete
otherwise, we add it for them.	Incomplete