[new][based on reverted project]admin can send join link to new instructors

1. redo the changes to the reverted project
2. now by default sample data will be imported for new instructor
3. modify the joinCourseForInstructor method to handle both instructors added by admin and other instructors
Professor @damithc  this "createInstructorAccount(instructorRole);" was from pervious code and it was doing double check to ensure the account was created for the instructor and it did not affect the admin adding instructor. I think it may not affect anything if it is deleted. I will delete it later