citra_qt: Add Game List configuration

This adds a Game List configuration group box which is similar to yuzu's, with features including icon size setting, row 1/2 text, and ability to hide invalid titles (those without a valid SMDH). I also added a UI tab and moved the language and theme settings there.

src/citra_qt/configuration/configure_general.h

@@ -24,12 +24,6 @@ public:
     void applyConfiguration();
     void retranslateUi();
 
-private slots:
-    void onLanguageChanged(int index);
-
-signals:
-    void languageChanged(const QString& locale);
-
 private:
     void setConfiguration();