[kernel] Move bind_irq syscall to new system object

In order to implement capabilities on system resources like IRQs so that
they may be restricted to drivers only, add a new 'system' kobject type,
and move the bind_irq functionality from endpoint to system.

Also fix some stack bugs passing the initial handles to a program.

src/kernel/objects/system.h

@@ -0,0 +1,18 @@
+#pragma once
+/// \file system.h
+/// Definition of kobject type representing the system
+
+#include "objects/kobject.h"
+
+class system :
+	public kobject
+{
+public:
+	static constexpr kobject::type type = kobject::type::event;
+
+	inline static system * get() { return &s_instance; }
+
+private:
+	static system s_instance;
+	system() : kobject(type::system) {}
+};