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/Directory.cpp

@@ -6,6 +6,7 @@
 
 #include <Kernel/FileSystem/SysFS/RootDirectory.h>
 #include <Kernel/FileSystem/SysFS/Subsystems/Devices/Directory.h>
+#include <Kernel/FileSystem/SysFS/Subsystems/Devices/Graphics/Directory.h>
 #include <Kernel/FileSystem/SysFS/Subsystems/Devices/Storage/Directory.h>
 #include <Kernel/Sections.h>
 
@@ -16,6 +17,7 @@ UNMAP_AFTER_INIT NonnullRefPtr<SysFSDevicesDirectory> SysFSDevicesDirectory::mus
     auto devices_directory = adopt_ref_if_nonnull(new (nothrow) SysFSDevicesDirectory(root_directory)).release_nonnull();
     MUST(devices_directory->m_child_components.with([&](auto& list) -> ErrorOr<void> {
         list.append(SysFSStorageDirectory::must_create(*devices_directory));
+        list.append(SysFSGraphicsDirectory::must_create(*devices_directory));
         return {};
     }));
     return devices_directory;