Kernel/SysFS: Add /sys/devices/storage directory

This change in fact does the following:
1. Use support for symlinks between /sys/dev/block/ storage device
identifier nodes and devices in /sys/devices/storage/{LUN}.
2. Add basic nodes in a /sys/devices/storage/{LUN} directory, to let
userspace to know about the device and its details.

Kernel/FileSystem/SysFS/Subsystems/Devices/Directory.h

@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2022, Liav A. <liavalb@hotmail.co.il>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <Kernel/FileSystem/SysFS/Component.h>
+#include <Kernel/Forward.h>
+
+namespace Kernel {
+
+class SysFSDevicesDirectory final : public SysFSDirectory {
+public:
+    virtual StringView name() const override { return "devices"sv; }
+    static NonnullRefPtr<SysFSDevicesDirectory> must_create(SysFSRootDirectory const&);
+
+private:
+    explicit SysFSDevicesDirectory(SysFSRootDirectory const&);
+};
+
+}