[Python][FlightRPC] Use `FlightStreamReader` & `FlightStreamWriter` in `do_exchange()`

[pvardanis]

Describe the usage question you have. Please include as many useful details as possible.

I have an implementation for do_exchange() that reads/writes over a pa.RecordBatch using pa.MetadataRecordBatchReader and pa.MetadataRecordBatchWriter respectively. Is it possible to stream outputs using the stream equivalent instead? The RPC reads the output from an LLM in a streaming manner and I want to be able to stream results back to the client as soon as they're generated at each iteration.

Component(s)

FlightRPC, Python