MAINT: Testing mega-effort

[jerdra]

niviz-rater was a cow-boy project of trying to solve the problem of QC sucking. As a result, its lacking in structure and testing. This issue is my hopes and dreams of making this a properly set up project. Tests are needed for the following major items:

Backend

1. index.py does it create the correct database when initialized?
2. api.py does it return the correct values from GET requests
3. api.py does it implement the current SQL calls on POST requests

Note that part of this may require some refactoring to make sure that the backend is sufficiently testable

Frontend

Svelte is relatively new territory for me, but this is probably a good place to start:

https://github.com/testing-library/svelte-testing-library