Refactor AuthenticatedState to store displayName and uid

The AuthenticatedState interface was updated to directly store the
`displayName` and `uid` properties. Previously, it stored the entire
`CasContent` object, which contained these properties along with others
that were not consistently used. This change simplifies the interface
and reduces redundancy.

defaults/interfaces.ts

@@ -5,7 +5,8 @@ export interface AuthenticatedState {
   isAuthenticated: true;
   isFromPolytech: boolean;
   role: "etudiant" | "professeur" | "administration" | "autre";
-  session: CasContent;
+  displayName: string;
+  uid: string;
   availablePages: Record<string, string>;
 }