[FEATURE] Add Swagger UI for API

## Feature Description

Add Swagger UI to the application. It should autogenerate docs and an endpoint testing UI from pydantic request and response data within the route source code.

## Why It's Worth Implementing

This provides a helpful way for the frontend engineering team to understand and interact with the API during the frontend buildout as part of `v2.0`. It also will allow easy testing for the backend engineering team.

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## Acceptance Criteria & Solution Requirements
*To close this issue, the following must be met (can be finalized in the comments):*
- [x] 1. Application runs as expected with the new feature integrated seamlessly.
- [x] 2. Code quality metrics are maintained, and linting has been considered in development.
- [x] 3. Testing metrics are maintained, and tests have been updated/added wherever relevant during development.
- [x] 4. Documentation has been updated to reflect the changes made during development.
- [x] 5. Add the new `flask-openapi3` dependency.
- [x] 6. Add the new `OpenAPI` extension and include it in `create_app()`.