Refactor: Consolidate role-specific pages and directories

### Description
* Do not create separate pages for Admin, Mentor, and Student.This duplicates code for no reason, especially since a lot of the UI and UX are similar for the same page across roles. 
* Consolidate the following directories into single files that render the UI and display info according to roles: 
  * `database-updates/` 
  * `orders/` 
  * `projects/` 
  * `reimbursement/` 