Separate the concepts of archived and disconnected devices

Summary:
Minor code cleanup to avoid future confusion:

- archived: a device that was imported from a Flipper trace, and only has persisted state
- (dis)connected: a real stateful device that might or might not have an active connection

Reviewed By: nikoant

Differential Revision: D26275459

fbshipit-source-id: eba554b37c39711e367c3795ff4456329a303c22

desktop/app/src/PluginContainer.tsx

@@ -588,7 +588,7 @@ export default connect<StateFromProps, DispatchFromProps, OwnProps, Store>(
     }
     const isArchivedDevice = !selectedDevice
       ? false
-      : selectedDevice instanceof ArchivedDevice;
+      : selectedDevice.isArchived;
     if (isArchivedDevice) {
       pluginIsEnabled = true;
     }