Kernel/SysFS: Add exposing interface for DisplayConnectors

Under normal conditions (when mounting SysFS in /sys), there will be a
new directory in the /sys/devices directory called "graphics".
For now, under that directory there will be only a sub-directory called
"connectors" which will contain all DisplayConnectors' details, each in
its own sub-directory too, distinguished in naming with its minor
number.

Therefore, /sys/devices/graphics/connectors/MINOR_NUMBER/ will contain:
- General device attributes such as mutable_mode_setting_capable,
  double_buffering_capable, flush_support, partial_flush_support and
  refresh_rate_support. These values are exposed in the ioctl interface
  of the DisplayConnector class too, but these can be useful later on
  for command line utilities that want/need to expose these basic
  settings.
- The EDID blob, simply named "edid". This will help userspace to fetch
  the edid without the need of using the ioctl interface later on.

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

@@ -0,0 +1,26 @@
+/*
+ * 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/FileSystem/SysFS/Subsystems/Devices/Directory.h>
+#include <Kernel/Forward.h>
+
+namespace Kernel {
+
+class SysFSGraphicsDirectory : public SysFSDirectory {
+    friend class SysFSComponentRegistry;
+
+public:
+    virtual StringView name() const override { return "graphics"sv; }
+    static NonnullRefPtr<SysFSGraphicsDirectory> must_create(SysFSDevicesDirectory const&);
+
+private:
+    explicit SysFSGraphicsDirectory(SysFSDevicesDirectory const&);
+};
+
+}