Optimize Mentorship app ModuleNode

**Describe the solution you'd like**
1. Complex optimization hint (with Prefetch) or a new dataloader for the mentors resolver
2. New loader for mentees resolver to load users based on mentee_users
3. New loader for issue_mentees resolver to load users based on issue_number
4. New loader for issues resolver to load issues based on Module ID
5. Loader for issue_by_number resolver (the same as above)
6. New loader for interested_users to load based on issue_number
7. New loader for recent_pull_requests resolver to load based on module issues
8. Optimization hint for project_name
9. Complex Optimization hint for issues_count
10. Complex Optimization hint for available_labels
11. Complex Optimization hint for task_deadline
12. Complex Optimization hint for task_assigned_at

**Are you going to work on implementing this?**

- [x] Yes
- [ ] No