Noref/fix solution types

[ClayBenson94]

NOREF

Description

• Updates SQL types and migrations to reference CONTRACTOR as a SolutionType instead of CONTRACT (which appeared to just be a typo/mismatch from SQL to GQL)

How to test this change

1. Ensure that adding a custom solution through postman with the CONTRACTOR type works as expected

Before

Below is a screenshot of the failure you'll see outside this branch, courtesy of @garyjzhao

After

PR Author Checklist

• I have provided a detailed description of the changes in this PR.
• I have provided clear instructions on how to test the changes in this PR.
• I have updated tests or written new tests as appropriate in this PR.
• Updated the Postman Collection if necessary.

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  • e.g. "Approving because the change is simple and matches the Figma design"
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[garyjzhao]

LGTM