citra, citra_qt: Add video dumping config read/write

The default values are VP9/libvorbis just like before. The default configuration is provided for VP9

src/citra_qt/configuration/config.h

@@ -44,6 +44,7 @@ private:
     void ReadUpdaterValues();
     void ReadUtilityValues();
     void ReadWebServiceValues();
+    void ReadVideoDumpingValues();
 
     void SaveValues();
     void SaveAudioValues();
@@ -65,6 +66,7 @@ private:
     void SaveUpdaterValues();
     void SaveUtilityValues();
     void SaveWebServiceValues();
+    void SaveVideoDumpingValues();
 
     QVariant ReadSetting(const QString& name) const;
     QVariant ReadSetting(const QString& name, const QVariant& default_value) const;