Introducing ArrowNativeTypeOp made it impossible to call kernels from generics

[bjchambers]

I previously had generic code along the lines of the following (it was actually in evaluator structs, as part of implementing a query evaluator):

fn<T: ArrowNumericType> perform_math(lhs: &PrimitiveArray<T>, rhs: &PrimitiveArray<T>) -> anyhow::Result<ArrayRef>
  where T::Native: std::ops::Add<Output = T::Native> {
  Ok(Arc::new(arrow::compute::add::<T>(lhs.as_ref(), rhs.as_ref())?)
}

Now, the arrow::compute::add kernel (and many others) require T::Native: ArrowNativeTypeOp. I tried to update my code to add that to the where clause, but it isn't possible, since the ArrowNativeTypeOp is a public trait inside a crate-scoped module.

As far as I can tell this makes it impossible to call any of the kernels that require ArrowNativeTypeOp from within code that is generic over the numeric type... which seems like it would be pretty useful. Could the ArrowNativeTypeOp be re-exported to support declaring such constraints?