Support JsonStreamWriter Interface like java client.

[slice-amandata]

Hi,

i recently started using storage write api and python client only supports protobuf methods to ingest the data into bigquery.it is kind of frustrating to use it lack of example etc.JsonStreamWriter will definitely improve the developer experience.

When will python storage client going to support it ?

[parthea]

This issue was transferred from python-bigquery-storage to google-cloud-python as part of the work for https://github.com/googleapis/google-cloud-python/issues/10991.