Common/Result: Swap order of template parameters to match C++26's std::expected, make all member functions constexpr, and add moving "unexpected" conversion constructor for consistency.

Source/Core/DiscIO/MultithreadedCompressor.h

@@ -8,8 +8,6 @@
 #include <memory>
 #include <thread>
 #include <utility>
-#include <variant>
-#include <vector>
 
 #include "Common/Assert.h"
 #include "Common/Event.h"
@@ -27,7 +25,7 @@ enum class ConversionResultCode
 };
 
 template <typename T>
-using ConversionResult = Common::Result<ConversionResultCode, T>;
+using ConversionResult = Common::Result<T, ConversionResultCode>;
 
 // This class starts a number of compression threads and one output thread.
 // The set_up_compress_thread_state function is called at the start of each compression thread.