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.cpp

@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2022, Liav A. <liavalb@hotmail.co.il>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <Kernel/FileSystem/SysFS/Subsystems/Devices/Graphics/Directory.h>
+#include <Kernel/FileSystem/SysFS/Subsystems/Devices/Graphics/DisplayConnector/Directory.h>
+#include <Kernel/Sections.h>
+
+namespace Kernel {
+
+UNMAP_AFTER_INIT NonnullRefPtr<SysFSGraphicsDirectory> SysFSGraphicsDirectory::must_create(SysFSDevicesDirectory const& parent_directory)
+{
+    auto directory = adopt_ref(*new (nothrow) SysFSGraphicsDirectory(parent_directory));
+    MUST(directory->m_child_components.with([&](auto& list) -> ErrorOr<void> {
+        list.append(SysFSDisplayConnectorsDirectory::must_create(*directory));
+        return {};
+    }));
+    return directory;
+}
+
+UNMAP_AFTER_INIT SysFSGraphicsDirectory::SysFSGraphicsDirectory(SysFSDevicesDirectory const& parent_directory)
+    : SysFSDirectory(parent_directory)
+{
+}
+
+}