feat: add endpoint and email for deleting accounts with incorrect email (AAI-829)

[marius-mather]

Description

AAI-829: add an endpoint to delete accounts with incorrect email - and notify users.

Changes

• Switch to Jinja2 templates for emails - less HTML in our code, and allows tighter control of escaping and template variables
• Add template for notifying users about incorrect emails
• Admin endpoint: POST /users/{user_id}/delete_invalid_email
• Unit tests

Checklist

• I have commented my code, particularly in hard-to-understand areas
• I have added unit / integration tests that prove my fix is effective or that my feature works
• I have run all tests locally and they pass
• I have updated the documentation (if applicable)
• For any new secrets, I have updated the shared spreadsheet and the GitHub Secrets.

How to Test Manually (if necessary)

Run uv run pytest

Example email:

[minh-biocommons]

Everything looks good to me, good separation of concerns!