[refactor] Refactor the tutorial code

[b-pos465]

The tutorial code has been implemented in the last iteration of my master thesis. The code is not perfect and does not fit into the state logic of the model.

We should split the TutorialStateController and find a solution how to enable and disable all relevant elements in the app to prevent the user from taking unwanted paths: One example is the close buttons of any dialog which is always available - even if it is not the current task in the tutorial.