This program runs in Ring 3 and needs IO permissions to read data from port 0x60.
It uses the await_interrupt EuraliOS syscall to wait for an interrupt to occur;
reads the scancode from port 0x60; passes the scancode to the pc_keyboard crate;
and then sends the corresponding character (if any) in a message to STDOUT.
The init program starts this keyboard driver, configuring it so that keyboard’s
STDOUT is connected to the init’s STDIN.