Common: Move asserts to their own header

Source/Core/DiscIO/VolumeDirectory.cpp

@@ -10,10 +10,12 @@
 #include <string>
 #include <vector>
 
+#include "Common/Assert.h"
 #include "Common/CommonPaths.h"
 #include "Common/CommonTypes.h"
 #include "Common/FileUtil.h"
 #include "Common/MathUtil.h"
+#include "Common/Logging/Log.h"
 #include "DiscIO/FileBlob.h"
 #include "DiscIO/FileMonitor.h"
 #include "DiscIO/Volume.h"