Implement batch user retrieval in AdminController and update routes

- Added a new method `getUsers` in AdminController to handle batch retrieval of user information based on hashed IDs.
- Updated adminRouter to include a new route for batch user retrieval.
- Enhanced AdminService with a method to fetch user details by hashed IDs, ensuring proper access control.
- Updated localization files to include the new "username" field for user connections in both German and English.
- Modified ServicesStatusView to utilize the new batch user retrieval for displaying usernames alongside connection counts.

backend/services/adminService.js

@@ -441,6 +441,30 @@ class AdminService {
         return { id: user.hashedId, username: user.username, active: user.active, registrationDate: user.registrationDate };
     }
 
+    async getUsersByHashedIds(requestingHashedUserId, targetHashedIds) {
+        if (!(await this.hasUserAccess(requestingHashedUserId, 'useradministration'))) {
+            throw new Error('noaccess');
+        }
+        if (!Array.isArray(targetHashedIds) || targetHashedIds.length === 0) {
+            return [];
+        }
+        const users = await User.findAll({
+            where: { hashedId: { [Op.in]: targetHashedIds } },
+            attributes: ['id', 'hashedId', 'username', 'active', 'registrationDate']
+        });
+        // Erstelle ein Map für schnellen Zugriff
+        const userMap = {};
+        users.forEach(user => {
+            userMap[user.hashedId] = {
+                id: user.hashedId,
+                username: user.username,
+                active: user.active,
+                registrationDate: user.registrationDate
+            };
+        });
+        return userMap;
+    }
+
     async updateUser(requestingHashedUserId, targetHashedId, data) {
         if (!(await this.hasUserAccess(requestingHashedUserId, 'useradministration'))) {
             throw new Error('noaccess');