[Groups] View single group details (GET /groups-management/groups/{id})

[TheRealSeber]

Implement the frontend logic and UI to fetch and display the details of a single group using GET /groups-management/groups/{id}.

Requirements

• Create a page/dialog/component to view group info and users.
• Use a remote function: GET /groups-management/groups/{id}.
• Follow Tasks management UI conventions for details views.
• Handle loading, error, and not found states.
• Support i18n and extensible permissions integration.

Child of [Groups] Implement groups management for teachers (parent issue): #139 READ IT before implementing anything