feat: BigQuery Storage v1beta1 API migration guide

[benhxy]

Description

Fixes b/505001153. BigQuery Storage team is planning to deprecate v1beta1 API. This PR adds a migration guide from v1beta1 to v1.

Note: Before submitting a pull request, please open an issue for discussion if you are not associated with Google.

Checklist

• I have followed guidelines from CONTRIBUTING.MD and Samples Style Guide
• Tests pass: npm test (see Testing)
• Lint pass: npm run lint (see Style)
• Required CI tests pass (see CI testing)
• These samples need a new API enabled in testing projects to pass (let us know which ones)
• These samples need a new/updated env vars in testing projects set to pass (let us know which ones)
• This pull request is from a branch created directly off of GoogleCloudPlatform/nodejs-docs-samples. Not a fork.
• This sample adds a new sample directory, and I updated the CODEOWNERS file with the codeowners for this sample
• This sample adds a new sample directory, and I created GitHub Actions workflow for this sample
• This sample adds a new Product API, and I updated the Blunderbuss issue/PR auto-assigner with the codeowners for this sample
• Please merge this PR for me once it is approved

Note: Any check with (dev), (experimental), or (legacy) can be ignored and should not block your PR from merging (see CI testing).

[gemini-code-assist]

Code Review

This pull request introduces migration guides for transitioning the BigQuery Storage API from v1beta1 to v1 in JavaScript and TypeScript. The review feedback suggests adding safety checks in the JavaScript guide to prevent potential runtime errors when accessing streams, and correcting code comments in both guides that incorrectly reference a rowCount property on avroRows instead of the top-level response object.

[feywind]

@iennae Do you mind assigning this to someone appropriate? I need to take myself off the sample reviewers list, I think.

[angelcaamal]

Everything looks good to me, but there is a CODEOWNERS error on line 46:

Unknown owner on line 46: make sure the team @GoogleCloudPlatform/bigquery-readapi-team exists, is publicly visible, and has write access to the repository

[benhxy]

Hmm that's strange. https://github.com/orgs/GoogleCloudPlatform/teams/bigquery-readapi-team clearly exists

[amcolin]

LGTM

[benhxy]

Thank you! Can you please help me merge this PR? I don't have the permission to do so...