[DBX-94128] update 526 remediation model for email era

[SamStuckey]

Summary

• This work is behind a feature toggle (flipper): NO
• migration to add remediation_type value to to Form526SubmissionRemediation table
• follow ups
  • refactor the model to have an enum that leverages this value providing types
    • manual
    • ignored_as_duplicate
    • email_notification
  • migrate application logic
    • update existing ignored_as_duplicate: true values to new paradigm
    • update Form526Submission state scopes to use new paradigm
  • remove ignored_as_duplicate value

This will unblock iterations on our 526 Silent Failure work. We will use this new paradigm to automatically 'remediate' submissions when we notify a veteran via email of a failure

Related issue(s)

• Ticket for work
• Form 526 Scopes documentation

Testing done

• New code is covered by unit tests (n/a)
• nothing to test

What areas of the site does it impact?

Form526Submission silent failures

Acceptance criteria

• I fixed|updated|added unit tests and integration tests for each feature (if applicable).
• No error nor warning in the console.
• Events are being sent to the appropriate logging solution
• Documentation has been updated (link to documentation)
• No sensitive information (i.e. PII/credentials/internal URLs/etc.) is captured in logging, hardcoded, or specs
• Feature/bug has a monitor built into Datadog (if applicable)
• If app impacted requires authentication, did you login to a local build and verify all authenticated routes work as expected
• I added a screenshot of the developed feature

Requested Feedback

(OPTIONAL)What should the reviewers know in addition to the above. Is there anything specific you wish the reviewer to assist with. Do you have any concerns with this PR, why?

[kylesoskin]

The PR mentions removing the ignored_as_duplicate value, does that mean removing a column? Or what does that mean.

Edit: NVM I see that as a follow up, so that is safe to do as another PR with a migration of data from that column to this new one?

[SamStuckey]

@kylesoskin we can discuss how to migrate the data in subsequent work. but TL;DR we could do a one line rake task or just command line it

[github-actions]

Backend-review-group approval confirmed.