[FSSDK-11362] Fix CSRF security warning

[pvcraven]

Summary

• PRISMA is complaining about CSRF protections being disabled in a unit test for a flask app. While not really a vulnerability, good to show proper security even in an example/test. So update to enable CSRF.

Test plan

Run tests.

Issues

• FSSDK-11362

[Copilot]

Pull Request Overview

This PR addresses the CSRF security warning issue by enabling CSRF protection in a Flask test application to better demonstrate secure practices, even in test scenarios.

• Moved and updated Flask imports to include CSRFProtect.
• Initialized CSRF protection for the test app.
• Added a lint directive for a global variable declaration in the after_request handler.

[Copilot]

Enabling CSRF protection in the test application may cause tests to fail if CSRF tokens are not provided. Consider updating your test configuration or request simulation to correctly handle CSRF tokens.