feat: add cloud workflow for exporting vector data from Bigtable to Vertex Vector Search

[ron-gal]

…x Vector Search

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This is a Bigtable version of https://github.com/cloudspannerecosystem/spanner-ai. Most of the work was copy pasting the Spanner code and adjusting it for Bigtable.

Fixes # 🦕

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[daniel-sanche]

I'm not sure this is the right place for this kind of content. Usually, the samples/ directory would just contain code snippets surrounded by region tags, that are then pulled into user-facing content on the docsite and/or in the library documentation in the docs/ folder. I'm not really seeing any region tags in this PR, and it seems more like a full tutorial. Are you sure this is the right place for it? Have you discussed this with the tech writers?

I'd probably suggest moving the contents of this README to a page on the docsite, pulling in some snippets like this one to show how to interact with it using Python, and linking to that page in the README here. But let me know if you've already considered that

[ron-gal]

Merged in https://github.com/GoogleCloudPlatform/workflows-demos/pull/114