Move user directory detection location to UICommon.

The UI should decide on where it wants the user directory, not our core system.
This is in anticipation of some upcoming work on Android which will need proper user directory setting.

Source/Core/DolphinQt/Main.cpp

@@ -42,6 +42,7 @@ int main(int argc, char* argv[])
 	app.setAttribute(Qt::AA_UseHighDpiPixmaps);
 	// TODO: Add command line options
 
+	UICommon::SetUserDirectory(""); // Auto-detect user folder
 	UICommon::CreateDirectories();
 	UICommon::Init();