ES|QL `toArrowReader` does not properly handle ReadableStream responses

[JoshMock]

toArrowReader currently assumes the type of a streaming response is a Buffer rather than a ReadableStream, and the apache-arrow package correctly detects the type at runtime and returns an asynchronous iterable in the latter case. The helper code does not properly account for this, nor do the unit tests or the documentation for this helper function.

[JoshMock]

I was able to update the code to ensure that it correctly assumes the value will be an AsyncRecordBatchStreamReader rather than a RecordBatchStreamReader, which means that iterating will require using for await (...) rather than for (...).

This leads to a new problem, which I'm still trying to unravel: Undici throws a RequestAbortedError when a stream is destroyed before an end event is emitted, and Arrow destroys the stream as part of its cleanup, presumably before the end has been emitted.

Trying to find a way to ensure that this is cleaned up properly without aborting the request or, if necessary, listening to and silencing the abort event on the request's ReadableStream so it does not raise an error.