Minor annoyance with the util crate

[davisp]

Describe the bug

Working with the new util crate finally and I hit a minor snag. Attempting to use datafusion_python_util::to_datafusion_err; results in a function to_datafusion_err is private. Luckily it can just be imported from the nested errors module.

To Reproduce

use datafusion_python_util::to_datafusion_err;

Expected behavior

I'm not entirely sure on this one. I could go either way on making the import in lib.rs a pub use here or we could remove the use completely to avoid the symbol existing so that the standard is to use from the errors module.

Additional context

That pretty much sums it up.

[kevinjqliu]

I think marking it pub use makes sense here. to_datafusion_err is already marked as a public function in errors.rs, so this just makes it consistently accessible from the crate root as users would expect.