Back up and restore custom role names even if there is no user enrolled with those roles

There might be a case when academics rename roles in their courses and would want to retain all these custom names when backing up and restoring/copying courses.
Currently, custom role names are restored/copied only if there are users enrolled with these roles. So this may lead to a scenario when someone created a course, renamed all the roles, enrolled students, copied the course and in the target course only student role will be still renamed and all other roles will have their default system name.