User interface for admin (iOS, iPadOS)

[BK-Teisrud]

As of today, there is no user interface for admin in the swiftUI application.

An admin needs:

• A list of all QuickFeed users
• A list of all the courses on QuickFeed
• A way to add new courses
• A way to edit existing courses
• A way to promote or take away administrator rights from other users

Should work in both dark and light mode