Recover move right/left functionality removed/hidden for 4.0 (backport of MDL-76990)

(Copied from MDL-76990 ) Mainly covered by behat and unit tests. Manual test to check the UI As admin create a course with 2 different activities. Go to the course and turn editing on. Open the action menu for the first activity.  Confirm there is a 'Move right' action. Confirm there is no 'Move left' action. Click on 'Move right' action. Confirm the first  activity card has no border anymore. Confirm the left margin of the first activity card is bigger than the rest of the activities. Open the action menu for the second activity. Click on 'Move right' action. Confirm the second activity card has top border only. Confirm the top border of the second activity is not rounded. Confirm the left margin of the second activity card is bigger than before moving activity to the right. Open the action menu for the first activity. Click on 'Move left' action. Confirm the first activity has a full border. Confirm the second activity has no border. Confirm the left margin of the first activity is the same as the beginning.