general: Make CPU accuracy and related a Settings::Setting

Required to make CPU accuracy and unsafe settings available to use as a
per-game setting.

src/yuzu/configuration/config.h

@@ -132,5 +132,6 @@ private:
 };
 
 // These metatype declarations cannot be in common/settings.h because core is devoid of QT
+Q_DECLARE_METATYPE(Settings::CPUAccuracy);
 Q_DECLARE_METATYPE(Settings::RendererBackend);
 Q_DECLARE_METATYPE(Settings::GPUAccuracy);