As a teacher
I want to be able to indent activities
so I could simulate a hierarchy on my course

Move right/left functionality was removed from Moodle 4.0. We want to recover the functionality as in 3.11 but with some changes:

• This issue doesn't include any migration/upgrading process. So the value for 'indent' field in the course_modules table of the database won't change by default.
• There is only one indentation level allowed. So the teacher could move the activity once to the right. That means that when the teacher moves any activity to the right, the new value for 'indent' field in the 'course_modules' table will be 1.  And when the teacher moves any activity to the left, the new value for 'indent' field in the 'course_modules' table will be 0. Whatever the previous value of the 'indent' field was.
• For activities with 'indent' value 0 or any negative value, there will be an option to 'Move right', but not to 'Move left'.* 
• For activities with 'indent' value higher than 0, there will be an option to 'Move left', but not to 'Move right'.*
• For activities with 'indent' value higher than 0, the activity card will have a bigger margin on the left part as shown in the prototype.*

*: Remember for RTL languages the functionality should be the opposite, as in 3.11

Note: A backporting request would be raised once this issue is integrated,  so we should try to implement the patch following the rules to be backportable. More information about backporting request: https://moodledev.io/general/development/policies/backporting