support google-cloud-bigquery-storage v1 #629

Is your feature request related to a problem? Please describe.

I'm filing this in response to internal feedback 186096865

Error: module 'google.cloud.bigquery_storage_v1.types' has no attribute 'DataFormat'

I believe this is because the customer is using a 1.x version of google-cloud-bigquery-storage.

Describe the solution you'd like

(A) Ideally we'd have some code to support either 1.x or 2.x versions of google-cloud-bigquery-storage

Describe alternatives you've considered

• (B) Detect when 1.x is used and raise an appropriate exception asking to upgrade to 2.x
• (C) Detect ... and fallback to tabledata.list / getQueryResults + warn that the package should be upgraded

Additional context

N/A