DiscIO: Remove VolumeCreator

This file is pretty small now that it doesn't handle Wii
partitions anymore, so let's move its contents to Volume.cpp.
This is also more consistent with how blob creation works.

Source/Android/jni/MainAndroid.cpp

@@ -37,7 +37,6 @@
 
 #include "DiscIO/Enums.h"
 #include "DiscIO/Volume.h"
-#include "DiscIO/VolumeCreator.h"
 
 #include "UICommon/UICommon.h"