Integrate GraphQL into backend

The old stack used a separate NodeJS application for the GraphQL API. This was because I was learning how to do GraphQL and followed a tutorial that stepped through making a common GraphQL database shim.

Now with more advanced knowledge, the GraphQL API endpoint should be integrated into the app itself. This way separate stacks don't have to be deployed alongside this backend, regardless of the simplicity of the backend. Additionally, we can then unify the web-app's data transmission relying only on GraphQL in the far future.

- [x] Research GraphQL python libraries ([strawberry](https://github.com/strawberry-graphql/strawberry) looks great!)
- [x] Backend refactor
- [x] Class layout
- [ ] GraphQL server in python backend
- [ ] Use GraphQL for real-time updates
- [ ] Abolish legacy websocket endpoint