Add close app modal

[gmrabian]

Summary

Add modal to verify user wants to close the college app before doing so

Fixes #204

Type of change

• [x] New feature (non-breaking change which adds functionality)

How To Test

• Go to an application
• Click "Close application"
• Verify it shows the modal and modal actions do what you expect

Checklist:

• [x] My code follows the style guidelines of this project and has no linting errors
• [x] I have performed a self-review of my code
• [x] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation, including any applicable ADRs
• [x] My changes generate no new warnings
• [x] I have added tests that fail without these changes
• [x] New and existing tests (unit, integration, accessibility) pass locally
• [ ] Documentation updated
• [ ] If there are security concerns they are addressed or ticketed after being discussed