qt_themes: add themed connected/disconnected icons for dark and fix status bar theme updating

In dark theme, it is very hard to see the connected/disconnected icons because they are dark too. So I added two white-coloured icons for the dark theme. This also fixed an issue where theme update does not change the icon on the status bar.

dist/qt_themes/qdarkstyle/style.qrc

@@ -1,6 +1,8 @@
 <RCC>
   <qresource prefix="icons/qdarkstyle">
     <file alias="index.theme">icons/index.theme</file>
+    <file alias="16x16/connected.png">icons/16x16/connected.png</file>
+    <file alias="16x16/disconnected.png">icons/16x16/disconnected.png</file>
     <file alias="16x16/lock.png">icons/16x16/lock.png</file>
     <file alias="48x48/bad_folder.png">icons/48x48/bad_folder.png</file>
     <file alias="48x48/chip.png">icons/48x48/chip.png</file>

src/citra_qt/main.cpp

@@ -440,6 +440,8 @@ void GMainWindow::ConnectWidgetEvents() {
     connect(this, &GMainWindow::UpdateProgress, this, &GMainWindow::OnUpdateProgress);
     connect(this, &GMainWindow::CIAInstallReport, this, &GMainWindow::OnCIAInstallReport);
     connect(this, &GMainWindow::CIAInstallFinished, this, &GMainWindow::OnCIAInstallFinished);
+    connect(this, &GMainWindow::UpdateThemedIcons, multiplayer_state,
+            &MultiplayerState::UpdateThemedIcons);
 }
 
 void GMainWindow::ConnectMenuEvents() {

src/citra_qt/multiplayer/state.cpp

@@ -134,6 +134,14 @@ void MultiplayerState::OnAnnounceFailed(const Common::WebResult& result) {
         QMessageBox::Ok);
 }
 
+void MultiplayerState::UpdateThemedIcons() {
+    if (current_state == Network::RoomMember::State::Joined) {
+        status_icon->setPixmap(QIcon::fromTheme("connected").pixmap(16));
+    } else {
+        status_icon->setPixmap(QIcon::fromTheme("disconnected").pixmap(16));
+    }
+}
+
 static void BringWidgetToFront(QWidget* widget) {
     widget->show();
     widget->activateWindow();

src/citra_qt/multiplayer/state.h

@@ -46,6 +46,7 @@ public slots:
     void OnOpenNetworkRoom();
     void OnDirectConnectToRoom();
     void OnAnnounceFailed(const Common::WebResult&);
+    void UpdateThemedIcons();
 
 signals:
     void NetworkStateChanged(const Network::RoomMember::State&);