VolumeWiiCrypted: Replace ChangePartition with a partition parameter

By removing mutable state in VolumeWiiCrypted, this change makes
partition-related code simpler. It also gets rid of other ugly things,
like ISOProperties's "over 9000" loop that creates a list of
partitions by trying possible combinations, and DiscScrubber's
volume swapping that recreates the entire volume when it needs to
change partition.

Source/Core/DiscIO/VolumeCreator.h

@@ -7,18 +7,13 @@
 #include <memory>
 #include <string>
 
-#include "Common/CommonTypes.h"
-
 namespace DiscIO
 {
 class IVolume;
-class IBlobReader;
 
-std::unique_ptr<IVolume> CreateVolumeFromFilename(const std::string& filename,
-                                                  u32 partition_group = 0, u32 volume_number = -1);
+std::unique_ptr<IVolume> CreateVolumeFromFilename(const std::string& filename);
 std::unique_ptr<IVolume> CreateVolumeFromDirectory(const std::string& directory, bool is_wii,
                                                    const std::string& apploader = "",
                                                    const std::string& dol = "");
-void VolumeKeyForPartition(IBlobReader& _rReader, u64 offset, u8* VolumeKey);
 
 }  // namespace