Add permissions system

[Dawnkai]

The page could use a permission system, which will allow the superadmin to add users to specific roles/groups.
The way I see it, we could have the following groups:

• Guest, aka no roles (can only view overview page)
• User (can view overview page and sensor page)
• AI (can run predictions and change parameters - this prevents hostile users from spamming the server with prediction requests)
• Admin (can give other users permissions and change system settings)
• Banned (can only view overview, given to hostile users by admin, overwrites other non-admin roles)

This needs to be integrated between backend API, frontend and database.