add report page -need statistics for reason to leave the course

[YulikK]

Describe the feature
We need to add a window for those who leave the course so that we can understand the statistics and motivation of people who leave the course. I think it would be good to have a short list of checkboxes with reasons that caused a person to drop out of the course. We can also add a text field if a student wants to give a more detailed answer. I also think it is important to duplicate these reasons in Russian and English so as not to create additional difficulties, so that students do not skip the form because of the need to understand and translate. We also need the ability to view analytics on students and courses.

[pestler]