…for writing rows (#284)* WIP: write client sample* add sample with nullable types* add schema for all supported types* add complex types to code sample* refactor sample so that it can be tested* make test assertions more thorough* fix lint error* remove done TODO* address reviewer comments* fix tag mismatch* test on multiple regions* correct comments about why offset exists* upgrade g-c-b* WIP: invert stream using BiDi class* WIP: attempt to use Future for send instead* WIP: use futures, populated by background consumer* make sure stream is actually open before returning from open* copy close implementation from pub/sub* support extra metadata* process exceptions, add open timeout* sort imports* WIP: unit tests* drain futures when stream closes* update docs* add callbacks to detect when a stream fails* add unit tests* add sleep to loop waiting for RPC to be active* don't freeze if initial RPC fails* add needed initializations so done() functions* fail fast when there is a problem with the initial request* don't inherit concurrent.futuresIt's unnecessary and kept resulting in stuff getting stuck.* add unit test for open timeout* 🦉 Updates from OwlBotSeehttps://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md* add manual client to docs* typo in sample comments* force timeout and metadata to be kwargs* unify interface for sending row data* pull stream name from merged request* require newer proto-plus for copy_from methodCo-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

🤖 I have created a release \*beep\* \*boop\*---## [2.8.0](https://www.github.com/googleapis/python-bigquery-storage/compare/v2.7.0...v2.8.0) (2021-09-10)### Features* add `BigQueryWriteClient` where `append_rows` returns a helper for writing rows ([#284](https://www.github.com/googleapis/python-bigquery-storage/issues/284)) ([2461f63](https://www.github.com/googleapis/python-bigquery-storage/commit/2461f63d37f707c2d634a95d87b8ffc3e4af3686))---This PR was generated with [Release Please](https://github.com/googleapis/release-please). See [documentation](https://github.com/googleapis/release-please#release-please).