AAI-286 Trigger email verification resend

[marius-mather]

Description

AAI-286: admins need to be able to trigger email verification resending, to help troubleshoot user account issues

Changes

• Add endpoint: /users/{user_id}/verification-email/resend
• Add 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)

How to Test Manually (if necessary)

Run uv run pytest

[amandazhuyilan]

Looks good - thanks for the change!