Sp 1513 fe implement device dropdown and live status card presence vacancy (#179)

* Called the widget of presence sensor status widgets.

* Enahnced `PowerClampEnergyDataDeviceDropdown` design and made it a dropdown.

* connected the realtime feature to the occupancy side bar, but with a mock id.

* revert default tab to energyManagement.

lib/pages/analytics/services/realtime_device_service/firebase_realtime_device_service.dart

@@ -23,7 +23,7 @@ class FirebaseRealtimeDeviceService implements RealtimeDeviceService {
 
           return Status(
             code: status['code']?.toString() ?? '',
-            value: num.tryParse(status['value']?.toString() ?? '0'),
+            value: status['value']?.toString() ?? '',
           );
         }).toList();
       });