feat: add onCancel option to quizzes

[vherrmann]

With this pr I want to add the callback onCancel to the options of quiz objects. This callback is executed whenever the quiz is cancelled. I gave it the same type as onComplete:

  onCancel?: (summary: { character: string; totalMistakes: number }) => void;

All tests have passed on my machine.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.42%. Comparing base (4ec4eda) to head (3de527f).

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Additional details and impacted files

@@            Coverage Diff             @@
##           master     #316      +/-   ##
==========================================
+ Coverage   96.41%   96.42%   +0.01%     
==========================================
  Files          32       32              
  Lines        1144     1148       +4     
  Branches      212      213       +1     
==========================================
+ Hits         1103     1107       +4     
  Misses         37       37              
  Partials        4        4              

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[vherrmann]

I have just noticed that the even though quiz.cancel() is executed on animateCharacter it is not on e.g. showCharacter. Therefore this pr may not be that reasonable after all (since the feature would work in unexpected ways).