fix: app submission edge cases (#4550)

[ColinBuyck]

This PR addresses bloom-housing#2173

• Addresses the issue in full
• Addresses only certain aspects of the issue

Description

This PR protects two duplicate submission paths. The first being spam clicking the submission button which was caused by the button loadingMessage prop not sufficiently blocking the submission call which is captured here (bloom-housing/ui-seeds#98) and is now handled with a !submitting check at the top of the submit function. The second path was clicking back on the confirmation screen and clicking submit again. This is handled by redirecting the user if they already have a confirmation code since that is only saved on submitted applications.

Note that the ticket also includes reference to a "warning" but after talking to produce these two fixes are the desired behavior for handling this ticket.

How Can This Be Tested/Reviewed?

This can be tested on the public side by logging in, fill out an application, and attempt to spam click the submit button. Then, click the back button on the confirmation page and notice the toast and redirect. You should end up on the my applications page where you will only see one submission for your attempted spam click.

Then, repeat this process as a signed out user and you should be redirected to the listings page and only see one submission in the applications table (via db).

Author Checklist:

• Added QA notes to the issue with applicable URLs
• Reviewed in a desktop view
• Reviewed in a mobile view
• Reviewed considering accessibility
• Added tests covering the changes
• Made corresponding changes to the documentation
• Ran yarn generate:client and/or created a migration when required

Review Process:

• Read and understand the issue
• Ensure the author has added QA notes
• Review the code itself from a style point of view
• Pull the changes down locally and test that the acceptance criteria is met
• Either (1) explicitly ask a clarifying question, (2) request changes, or (3) approve the PR, even if there are very small remaining changes, if you don't need to re-review after the updates

[netlify]

✅ Deploy Preview for housing-sanjoseca-gov ready!

Name	Link
🔨 Latest commit	af63fc7
🔍 Latest deploy log	https://app.netlify.com/sites/housing-sanjoseca-gov/deploys/6792861594befb000835c708
😎 Deploy Preview	https://deploy-preview-833--housing-sanjoseca-gov.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[emilyjablonski]

🎏