Add a notebook test script.

[MarkDaoust]

Add a starter script for testing notebooks.

based on google3/devsite/tools/tensorflow/kokoro/tf_ecosystem/executor.py

This gets most notebooks passing, we can use it as a base to setup presubmits.

Some notebooks are still failing:

• /Users/markdaoust/Projects/cookbook/examples/Voice_memos.ipynb - api installs
• /Users/markdaoust/Projects/cookbook/examples/Agents_Function_Calling_Barista_Bot.ipynb - user input
• /Users/markdaoust/Projects/cookbook/quickstarts/PDF_Files.ipynb - needs to install pdf tools
• /Users/markdaoust/Projects/cookbook/quickstarts/Authentication_with_OAuth.ipynb - oauth + a problem with list models?
• /Users/markdaoust/Projects/cookbook/quickstarts/Tuning.ipynb - oauth + a problem with list models?

See also: google/generative-ai-docs#445

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[MarkDaoust]

It's still pretty rough, but it gets the notebooks run.

Some notebooks only run with api_key, others only with oauth. We'll need to fix this.

We should probably look at using colab's docker:

https://twitter.com/GoogleColab/status/1663594080436375558

Then run in GH actions or kokoro.

https://docs.github.com/en/actions/creating-actions/creating-a-docker-container-action

[Giom-V]

I think we should close this PR as it's quite old and some much has changed since then...