kernel: Move object class to its own source files

General moving to keep kernel object types separate from the direct
kernel code. Also essentially a preliminary cleanup before eliminating
global kernel state in the kernel code.

src/core/hle/kernel/wait_object.h

@@ -7,7 +7,7 @@
 #include <vector>
 #include <boost/smart_ptr/intrusive_ptr.hpp>
 #include "common/common_types.h"
-#include "core/hle/kernel/kernel.h"
+#include "core/hle/kernel/object.h"
 
 namespace Kernel {