Get rid of test_with()

[filipsch]

test_with() is responsible for a lot of code in pythonwhat. If we get rid of this function, we can remove a lines of code that work but are very ugly. This would involve rewriting some SCTs though, for 19 exercises to be precise (some are duplicates, i.e. archived course that was split into two to make them shorter):

  course_id count link                                 
      <int> <int> <chr>                                
1       998     9 https://www.datacamp.com/courses/998 
2      1531     3 https://www.datacamp.com/courses/1531
3      1606     1 https://www.datacamp.com/courses/1606
4      1607     6 https://www.datacamp.com/courses/1607