fix: Disconnect from room before app closes. (#218)

* fix: Disconnect from room before app closes.

* chore: add app state listener.

* Remove unused import.

* fix `flutter test`.

* singleton.

example/windows/flutter/generated_plugin_registrant.cc

@@ -8,6 +8,7 @@
 
 #include <connectivity_plus_windows/connectivity_plus_windows_plugin.h>
 #include <flutter_webrtc/flutter_web_r_t_c_plugin.h>
+#include <flutter_window_close/flutter_window_close_plugin.h>
 #include <livekit_client/live_kit_plugin.h>
 
 void RegisterPlugins(flutter::PluginRegistry* registry) {
@@ -15,6 +16,8 @@ void RegisterPlugins(flutter::PluginRegistry* registry) {
       registry->GetRegistrarForPlugin("ConnectivityPlusWindowsPlugin"));
   FlutterWebRTCPluginRegisterWithRegistrar(
       registry->GetRegistrarForPlugin("FlutterWebRTCPlugin"));
+  FlutterWindowClosePluginRegisterWithRegistrar(
+      registry->GetRegistrarForPlugin("FlutterWindowClosePlugin"));
   LiveKitPluginRegisterWithRegistrar(
       registry->GetRegistrarForPlugin("LiveKitPlugin"));
 }

example/windows/flutter/generated_plugins.cmake

@@ -5,6 +5,7 @@
 list(APPEND FLUTTER_PLUGIN_LIST
   connectivity_plus_windows
   flutter_webrtc
+  flutter_window_close
   livekit_client
 )