Support Steam Deck controls directly through hidraw

This reads Steam Deck controls bypassing Steam Input. This allows for access to
motion controls as well as independent access to thumb sticks, trackpads, and
back grip buttons.

Source/Core/InputCommon/ControllerInterface/ControllerInterface.cpp

@@ -34,6 +34,9 @@
 #ifdef CIFACE_USE_DUALSHOCKUDPCLIENT
 #include "InputCommon/ControllerInterface/DualShockUDPClient/DualShockUDPClient.h"
 #endif
+#ifdef CIFACE_USE_STEAMDECK
+#include "InputCommon/ControllerInterface/SteamDeck/SteamDeck.h"
+#endif
 
 ControllerInterface g_controller_interface;
 
@@ -78,6 +81,9 @@ void ControllerInterface::Initialize(const WindowSystemInfo& wsi)
 #ifdef CIFACE_USE_DUALSHOCKUDPCLIENT
   m_input_backends.emplace_back(ciface::DualShockUDPClient::CreateInputBackend(this));
 #endif
+#ifdef CIFACE_USE_STEAMDECK
+  m_input_backends.emplace_back(ciface::SteamDeck::CreateInputBackend(this));
+#endif
 
   // Don't allow backends to add devices before the first RefreshDevices() as they will be cleaned
   // there. Or they'd end up waiting on the devices mutex if populated from another thread.