Cleaning up Controller for Role based access.

This Merge request is regarding:

1. Fixing all broken links.
2. Cleaning the user side Controller.
3. Deleted RegisterController and migrated the register to UserController

What to test?

1. Controllers actions access are set according to roles. Refer to this excel sheet
2. Each user side controller should have a function to display and no actions like add, edit, delete should be present on the user side.
3. Admin side controllers are restricted.
4. There are still controllers left for setting up role-based access which are not mentioned in the above list.
5. Test all the Functionality like:
   • registering user
   • user login
   • Change password in profile edit
   • forgot password functionality
   • Setup roles for other users using the admin account
   • Check TwoFactor setup using login (by setting 2fa_status = 0 in DB)

Observations :

1. Most of index.ctp are passed with a full table, which makes the page heavy, which can be further optimized by passing required data from controller to view.
2. On how to setup roles-based access will be addressed in further PR after discussion with other developers. For now,
   a. User Side Controller can access index and view.
   b. Admin can access everything.
   c. Editor Role can access Admin/ArtifactsController 's add() and edit() functionality only with restricted access to admin dashboard.