Implement multiple choice ExerciseWidget

[agoscinski]

These are the notes from how we would like this to look like

mc1 = MultipleChoiceExercise(
    description='How many sides does a square have?',
    key='square_sides',
    options={
        'one': 'One side',
        'two': 'Two sides',
        'three': 'Three sides',
        'four': 'Four sides'        
    }

    # OK, and then key and what you display is the same,  you internally
    # do `options = {k: k for k in options}`
    options=['one', 'two', 'three', 'four'],
    allow_multiple=False, # Default False
    randomize_order=False # Default False
    )

### BEGIN HIDDEN TEST
assert mc1.answer == 'four'
### END HIDDEN TEST



mc1 = MultipleChoiceExercise(
    description='How many sides do a triangle or a square have?',
    key='square_sides',
    options={
        'one': 'One side',
        'two': 'Two sides',
        'three': 'Three sides',
        'four': 'Four sides'        
    }

    # OK, and then key and what you display is the same,  you internally
    # do `options = {k: k for k in options}`
    options=['one', 'two', 'three', 'four'],
    allow_multiple=True, # Default False
    randomize_order=False # Default False
    )

### BEGIN HIDDEN TEST
print(mc1.answer) # -> always returns a set, even if allow_multiple = False

assert mc1.check_correct_answers(['four', 'three'])
assert mc1.check_correct_answers('four', 'three')
assert mc1.check_correct_answers('four')
### END HIDDEN TEST



## Try on 3 students to see if the "time cost" for grading for the teacher does NOT scale with the number of students

The MultipleChoiceExercise would inherit from ExerciseWidget

scicode-widgets/src/scwidgets/exercise/_widget_exercise_registry.py

Line 18 in 44495c4

class ExerciseWidget:

One can look at the TextExercise for a simple implementation example inheriting from it https://github.com/osscar-org/scicode-widgets/blob/main/src/scwidgets/exercise/_widget_text_exercise.py to get an idea how to implement it.