[Backend Rewrite] Questions

[RobbinBaauw]

• Recreate all question related endpoints, see https://github.com/finitum/CSHub/tree/dev/cshub-server/src/endpoints/question. Note that the URLs could have better naming, so feel free to change URLs, HTTP verbs & request/response bodies where you see fit. This might require changing the database structure because we used inheritance on the current server and will most likely include changing the request/response bodies structure. This is fine, even preferable, the easier the better.
• Fix the server related bugs described in Question bugs #201