feat: Add finance advisor spanner demo

[anirbanbagchi1979]

Description

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Fixes #<issue_number_goes_here> 🦕

[holtskinner]

Please fix remaining lint errors and spelling errors:

https://github.com/GoogleCloudPlatform/generative-ai/actions/runs/10117965823?pr=901

[anirbanbagchi1979]

Please fix remaining lint errors and spelling errors:

https://github.com/GoogleCloudPlatform/generative-ai/actions/runs/10117965823?pr=901

Please fix remaining lint errors and spelling errors:

https://github.com/GoogleCloudPlatform/generative-ai/actions/runs/10117965823?pr=901

Done