feat: Style Guide & Scripts for Extracting Files from Google Drive

[avi9664]

📄 Description

• Extracting from GDrive - Added script templates & example Jupyter notebooks using infrastructure datasets to the utils folder.
  • In order for the examples to work, make sure your service account is shared with this folder.
  • Right now, the extraction scripts only work with .csv, .zip, and .geojson files. You can edit the gdrive_to_pandas.py file to support other file types; you would just need to know the MIME type of the file.
  • The error handling isn't quite there yet. I still need to write test cases.
• Style Guide - Added STYLE_GUIDE.md under src/ca_biositing/pipeline/docs. Feel free to restructure & edit as you please.

✅ Checklist

• I ran pre-commit run --all-files and all checks pass
• Tests added/updated where needed
• Docs added/updated if applicable
• I have linked the issue this PR closes (if any)

💡 Type of change

Type	Checked?
🐞 Bug fix	[ ]
✨ New feature	[x]
📝 Documentation	[x]
♻️ Refactor	[ ]
🛠️ Build/CI	[ ]
Other (explain)	[ ]

🧪 How to test

• The example notebook is utils\external_etl_notebook.ipynb. Try running it to see if it works on your local machine.
• Optionally, you can also create a new extract script using any of the templates and run it in external_etl_notebook.ipynb.

📝 Notes to reviewers

• I still haven't changed the transform and load functions yet in external_etl_notebook.ipynb; they're all commented out in the last cell.