Split /dev/di commands from DVDInterface

The various ioctls sometimes have different arguments than the DI command
registers, though they generally overlap.  There are also a bunch of ioctls
that don't even normally go into DVDInterface, just returning various data.
Some of the implemented ioctls are new to Dolphin.

Source/Core/Core/IOS/IOS.cpp

@@ -782,6 +782,9 @@ void Init()
       device->EventNotify();
   });
 
+  Device::DI::s_finish_executing_di_command =
+      CoreTiming::RegisterEvent("FinishDICommand", Device::DI::FinishDICommandCallback);
+
   // Start with IOS80 to simulate part of the Wii boot process.
   s_ios = std::make_unique<EmulationKernel>(Titles::SYSTEM_MENU_IOS);
   // On a Wii, boot2 launches the system menu IOS, which then launches the system menu