Fix Face/Touch recommendation duplicate submission

[aduth]

🛠 Summary of changes

Fixes an edge-case where an error may occur during redirect of skipped Face/Touch Unlock recommendation if user submits multiple times.

Fixes include:

• Use SubmitButtonComponent which has built-in duplicate submission prevention
• Provide fallback where nil redirect would otherwise be used

More explanation in related Slack thread: https://gsa-tts.slack.com/archives/C01710KMYUB/p1733496464529579

📜 Testing Plan

Verify no 500 errors in following test flow:

Reconfigure to force recommendation A/B test to always be visible:

# config/application.yml
recommend_webauthn_platform_for_sms_ab_test_account_creation_percent: 100

1. Go to http://localhost:3000
2. Click "Create an account"
3. Continue account creation up to MFA selection screen
4. At MFA selection screen, emulate mobile device using Chrome DevTools device emulation
5. Refresh the page
6. Select phone as your sole MFA
7. Setup phone
8. At Face/Touch recommendation screen, configure Chrome DevTools network throttling to slow network speed to more easily simulate the example
9. Click "Skip" multiple times in quick succession
10. Observe that you don't encounter an error