What

Allow users to provide a custom tokio runtime for guest IO tasks like HTTP requests.

Why

DataFusion usually advises people to use a dedicated tokio runtime for I/O task outside of the CPU-bound tokio runtime used for computation. At InfluxData we kinda enforce that by disabling I/O functionality for the DataFusion runtime altogether. This currently leads to panics during HTTP requests a la:

A Tokio 1.x context was found, but IO is disabled. Call `enable_io` on the runtime builder to enable IO.

How

Pass a runtime Handle around for I/O.