Add option to emit HID display toggle from F9 display key

[Jules-Bertholet]

By default, this key emits Win+P, which is not portable to non-QWERTY keyboard layouts and non-Windows OSes. This adds an option (off by default, set with 0x3E16 flag) to emit the HID display toggle key instead.

This flag should be exposed in the BIOS settings.

See discussion at https://community.frame.work/t/f9-display-switch-is-broken-on-non-qwerty-layouts/59773