Multiple-choice questions grid creator (front end)

Add the feature in the front end that allows the user to add for each multiple choice question a row of boxes representing the different answers for that question. In the exam's menu, the user (exam creator) shall select a problem and a new box shall appear under the problem details box. That new box shall be called "Add MC question" and shall allow the user to input the number of possible answers. Afterwards the user shall be able to click on the button "generate" which will generate a row of boxes that the user can drag and drop in the exam PDF. The user shall also be able to choose the add the feedback options and select the right answer to the MC question.

In the same "Add MC question" modal the user shall be able to choose from a three sorts of labels for the MC boxes: letters, numbers, true or false.

Later in the development we can expand this feature into allowing the user to drag and drop specific MC boxes such that they can be placed anywhere separately.