Implement the backend for the inviting page.

• Option to invite group of user to test
• Sorting records by school, score, or username
• Option to group records by school, quiz
• Option to limit the displayed records per group to a configurable number
• Pagination

Example search query
Here are some examples of the expected search queries that the backend should support:
?groupBy=[school,quiz]&limitBy=username&limit=4&desc: Group the results by quiz and then by school, limit by username, show 4 records per group, and sort in descending order.
?groupBy=[school]&limitBy=score&limit=4&desc&quiz=5: Group by school, limit by score, show 4 records per group, sort in descending order, and filter by quiz with the ID 5.