Number of Likes required set to something else than a percentage

[profgrumpy]

Some student feedback mentioned that they find it more intuitive if we require a minimum number of likes that corresponds to liking 1 justification per alternative per question. The gear menu for justifications in the quiz editor page only allowsus to set the value as a percentage of all justifications presented to the student. Add an option to require one justification per alternative (as minimal and maximal number of likes)