Add error messaging to Veteran Verification /status endpoint

[khenson-oddball]

Summary

• This work is not behind a feature toggle.
• This change adds error message logic to a new route for getting confirmation of a veteran's Title 38 status. This endpoint returns data from the Lighthouse Veteran Service History and Eligibility API /status endpoint, which will be used to determine if a veteran is eligible to view their Proof of Status card. If the veteran is found to be ineligible, this change provides more detailed information to display to the user to help them understand why and who to contact to correct it, if they choose.
• Documentation and further logging will be added in a forthcoming PR.
• I work on the IIR Product team and we currently own this feature.

Related issue(s)

• 1210

Testing done

• New code is covered by unit tests
• There is no old behavior, as this is a completely new implementation.

Screenshots

What areas of the site does it impact?

This change does not impact any areas outside of the newly added files.

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

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