Migrate bigquery storage SDK from v1beta1 to v1

[benhxy]

BigQuery Storage Read API v1 has been GA since 2020. Update the SDK from v1beta1 to v1 to prepare for v1beta1 deprecation.

Context: b/505001153

1. Service & Namespace Updates:

   • Renamed the service from BigQueryStorage to BigQueryRead as per the v1 transition.
   • Updated the namespace from google::cloud::bigquery::storage::v1beta1 to google::cloud::bigquery::storage::v1.
   • Updated C++ includes to use google/cloud/bigquery/storage/v1/storage.grpc.pb.h.

2. Request/Response Structure Changes:

   • CreateReadSession:
     • Replaced TableReference (nested fields) with a single table string formatted as projects/{project_id}/datasets/{dataset_id}/tables/{table_id}.
     • Moved DataFormat and ReadOptions into the read_session message.
     • Replaced requested_streams and sharding_strategy with max_stream_count in the top-level request.
   • ReadRows:
     • Updated ReadRowsRequest to use read_stream (string) and offset (int64) directly, replacing the old read_position message.
     • Moved row_count from AvroRows/ArrowRecordBatch to the top-level ReadRowsResponse.

3. Kernel & Library Refactoring:

   • bigquery_lib.h & bigquery_lib.cc: Updated the BigQueryClientResource to manage BigQueryRead::Stub and adjusted EnsureReaderInitialized and EnsureHasRow to use the v1 request/response fields.
   • bigquery_kernels.cc & bigquery_dataset_op.cc: Refactored the kernel implementation to construct the v1 CreateReadSessionRequest and process the updated ReadSession response.
   • bigquery_test_client_op.cc: Updated the test client to communicate with the v1 service.

4. Test Suite Updates:

   • tests/test_bigquery.py:
     • Migrated the FakeBigQueryServer to the v1 BigQueryRead service.
     • Updated Python imports to use google-cloud-bigquery-storage v1/v2 compatible paths.
     • Adjusted the mock server logic to handle the v1 table path parsing and the new ReadRows response structure.

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