API-23874 Track SC evidenceType on records

[cilestin]

Summary

This change tracks the evidence type a supplemental claim was submitted with, for business intelligence & statistics uses.

Update: I've verified the models in Production have the metadata key, as needed for this PR. Ready for review!

Related issue(s)

• https://vajira.max.gov/browse/API-23874
• API-23874 Add metadata to appeals tables #11788

Testing done

• Ensured creating a Supplemental Claim had its metadata['evidenceType'] filled as expected

What areas of the site does it impact?

• None, currently - the supplemental claims endpoints do not currently have a consumer.

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 or Grafana (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

[cilestin]

See #11788 for the database migration PR.

[michelpmcdonald]

Tested in staging using va.gov to create Supp claims, metadata does have the evidenceType now as expected:
metadata: {"evidenceType"=>["retrieval", "upload"]}