Settings: Move set defaults to HostInterface so it can use user paths

src/core/host_interface.h

@@ -116,6 +116,9 @@ protected:
   /// Returns the default path to a memory card for a specific game.
   std::string GetGameMemoryCardPath(const char* game_code, u32 slot);
 
+  /// Restores all settings to defaults.
+  void SetDefaultSettings();
+
   /// Applies new settings, updating internal state as needed. apply_callback should call m_settings.Load() after
   /// locking any required mutexes.
   void UpdateSettings(const std::function<void()>& apply_callback);