We can not handle collections in kwargs for UDFs

If a user uses a UDF that expects kwargs that are collections, then we can't handle this at the moment. This is a general issues for stuff like:

- map_partitions
- groupby.apply/transform
- map
- apply
- ...

This is a general problem that we should try to solve

Start by tracing how kwargs are handled across the listed UDF entry points: map_partitions, groupby.apply/transform, map, and apply. Define the expected behavior for collection-valued kwargs and verify that the solution works consistently across these operations.

Written by the indexing model from the issue text.