feat(genai): tools vais sample

[Guiners]

Description

Add new GenAI Vertex AI Search tool sample

• To make the Vertex AI Search tool with text sample work locally, a datastore had to be created and the Discovery Engine Editor role was required. This means the pipeline will fail without them.
• For reference, for this test I used the same datastore that is used in the corresponding Python sample: projects/{PROJECT_ID}/locations/global/collections/default_collection/dataStores/grounding-test-datastore

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).

[snippet-bot]

Here is the summary of changes.

You are about to add 1 region tag.

• genai/tools/tools-vais-with-txt.js:17, tag googlegenaisdk_tools_vais_with_txt

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