citra_qt: Use stylesheet with light colored icons if dark mode

dist/qt_themes/default/icons_light/index.theme

@@ -0,0 +1,13 @@
+[Icon Theme]
+Name=default
+Comment=default theme
+Directories=16x16,48x48,256x256
+ 
+[16x16]
+Size=16
+
+[48x48]
+Size=48
+ 
+[256x256]
+Size=256

dist/qt_themes/default/theme_default.qrc

@@ -17,7 +17,28 @@
         <file alias="48x48/star.png">icons/48x48/star.png</file>
         <file alias="256x256/plus_folder.png">icons/256x256/plus_folder.png</file>
     </qresource>
+    <qresource prefix="icons/default_with_light_icons">
+        <file alias="index.theme">icons_light/index.theme</file>
+        <file alias="16x16/checked.png">icons_light/16x16/checked.png</file>
+        <file alias="16x16/failed.png">icons_light/16x16/failed.png</file>
+        <file alias="16x16/connected.png">icons_light/16x16/connected.png</file>
+        <file alias="16x16/disconnected.png">icons_light/16x16/disconnected.png</file>
+        <file alias="16x16/connected_notification.png">icons_light/16x16/connected_notification.png</file>
+        <file alias="16x16/lock.png">icons_light/16x16/lock.png</file>
+        <file alias="48x48/bad_folder.png">icons_light/48x48/bad_folder.png</file>
+        <file alias="48x48/chip.png">icons_light/48x48/chip.png</file>
+        <file alias="48x48/folder.png">icons_light/48x48/folder.png</file>
+        <file alias="48x48/no_avatar.png">icons_light/48x48/no_avatar.png</file>
+        <file alias="48x48/plus.png">icons_light/48x48/plus.png</file>
+        <file alias="48x48/sd_card.png">icons_light/48x48/sd_card.png</file>
+        <file alias="256x256/citra.png">icons_light/256x256/citra.png</file>
+        <file alias="48x48/star.png">icons_light/48x48/star.png</file>
+        <file alias="256x256/plus_folder.png">icons_light/256x256/plus_folder.png</file>
+    </qresource>
     <qresource prefix="default">
         <file>style.qss</file>
     </qresource>
+    <qresource prefix="default_with_light_icons">
+        <file>style.qss</file>
+    </qresource>
 </RCC>

src/citra_qt/citra_qt.cpp

@@ -3477,9 +3477,20 @@ void GMainWindow::filterBarSetChecked(bool state) {
     emit(OnToggleFilterBar());
 }
 
+inline bool isDarkMode() {
+    const auto scheme = QGuiApplication::styleHints()->colorScheme();
+    return scheme == Qt::ColorScheme::Dark;
+}
+
 void GMainWindow::UpdateUITheme() {
     const QString icons_base_path = QStringLiteral(":/icons/");
-    const QString default_theme = QStringLiteral("default");
+    QString default_theme;
+    if (!isDarkMode()) {
+        default_theme = QStringLiteral("default");
+    } else {
+        default_theme = QStringLiteral("default_with_light_icons");
+    }
+
     const QString default_theme_path = icons_base_path + default_theme;
 
     const QString& current_theme = UISettings::values.theme;