Add Test Database connections

[mchlwellman]

User Story - Business Need

We currently do not have a way to include database operations in our unit tests. Add database setup and teardown functionality to the tests, and modify the existing db_init unit tests to use a real database engine, not a mocked one. This needs to be done for the notification api database.

• Sync with Kyle when ticket is picked up.
• Ticket is understood, and QA has been contacted (if the ticket has a QA label).

User Story(ies)

As a VANotify developer
I want reusable database sessions in my tests
So that I can accurately test functionality

Additional Info and Resources

• A helpful SA answer
• The existing notification api test database provisioning has a lot of anti-patterns so avoid re-using too much from that repo.

Acceptance Criteria

• The db_init tests use actual database connections, not mocked engines.
• This work is added to the sprint review slide deck (key win bullet point and demo slide)

QA Considerations

Potential Dependencies

• Updating existing unit tests