[UI, QUIZ] add route for previewing quiz question

[Felienne]

Idea incl level Testing the quiz is quite a hassle, cause to preview you have to click through all the questions. Can we make a route (like /quiz/1) to navigate to a specific question?

Note that we have this route:

But that is fetching, not rendering, rendering happens with a bit of js magic that I find hard to untangle, here: https://github.com/Felienne/hedy/blob/6c42e7e46476a338f1d488e9e41282ec411b0088/static/js/quiz.ts

Hopefully a front-ender can help me :)