Emit HID event when keyboard brightness changed via fn+space

[meijero-dot]

This applies to Framework laptop bios version 3.06 beta
Framework 13, 13th gen Intel

Bios update does not include a change to the EC that enables an OSD when changing the keyboard backlight brightness with fn+space under Linux. E.g, a Thinkpad running Linux shows an OSD similar to changing the brightness of the display.

For more information:
FrameworkComputer/EmbeddedController#53