Support the new user blocking feature

Test on a 3.6 site and a an older site. You will need two users and a course where both users are enrolled. 1. Login in the app with User 1. 2. Go to the course where both users are enrolled. 3. Go to Participants and open the profile of User 2. 4. Check that the button "Block user" is displayed in the profile. 5. Press the button and check that a confirmation modal is displayed with the name of User 2. 6. Press "Cancel" and check the "Block user" button is still displayed. 7. Press the "Block user" button again, but this time press "Block user" on the confirmation modal. 8. Check the "Block user" button is no longer displayed in the profile of User 2, instead "Unblock user" is displayed. 9. Login in Moodle web with User 2 and check that you cannot send a message to User 1. 10. Inn the app with User 1, open the profile of User 2. 11. Press the "Unblock user" button and check that a confirmation modal is displayed with the name of User 2. 12. Press "Cancel" and check the "Unblock user" button is still displayed. 13. Press the "Unblock user" button again, but this time press "Unblock user" on the confirmation modal. 14. Check the "Unblock user" button is no longer displayed in the profile of User 2, instead "Block user" is displayed. 15. Login in Moodle web with User 2 and check that you can send a message to User 1.