feat(mpi): redesign mpi schema

[alhayward]

Description

• Redefine the Master Patient Index (MPI) database schema using SQLAlchemy ORM
• Create an Alembic migration environment
• Generate an initial migration for the new schema

Schema

erDiagram
    Person {
        int id
        uuid internal_id
    }

    ExternalPerson {
        int id
        int person_id 
        string source
        string external_id
    }

    Patient {
        int id
        int person_id
        string data
    }

    BlockingKey {
        int id
        string key
    }

    BlockingValue {
        int id
        int patient_id
        int blockingkey_id
        string value
    }

    Person ||--o{ ExternalPerson: "has"
    Person ||--o{ Patient : "has"
    Patient ||--o{ BlockingValue : "has"
    BlockingKey ||--o{ BlockingValue: "has"

Related Issues

Closes #8

Checklist

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• [X] I have ensured that the pull request is of a manageable size, allowing it to be reviewed within a single session.
• [X] I have reviewed my changes to ensure they are clear, concise, and well-documented.
• [X] I have updated the documentation, if applicable.
• [X] I have added or updated test cases to cover my changes, if applicable.
• [X] I have minimized the number of reviewers to include only those essential for the review.
• [X] I have notified teammates in the review thread to build awareness.

Checklist for Reviewers

Please review and complete the following checklist during the review process:

• [ ] The code follows best practices and conventions.
• [ ] The changes implement the desired functionality or fix the reported issue.
• [ ] The tests cover the new changes and pass successfully.
• [ ] Any potential edge cases or error scenarios have been considered.

[ericbuckley]

@alhayward one last thing, please add yourself to the list of contributors in the pyproject.toml file