(Still in draft since I haven't yet added integration with SPI values)
v2: * Rebased on latest master, to pull in recent `server/queue.c` keyboard changes. * Autorepeat all keys, don't make exceptions for modifiers. * Autorepeat even if RIDEV_NOLEGACY. * Remove all uses of `current` thread from `queue_keyboard_messages`, so we can call it from the auto-repeat callback more easily.