Software hotkey support

[jackpot51]

Currently, some hotkeys are done in hardware.

The touchpad lock provides no visual notification of being activated, unlike the one we have from the WMI driver.

The keyboard brightness has no visual notification, and cannot be changed using software. On the darp5, the color of the keyboard is hardcoded and defaults to blue.

The airplane mode toggle has no visual notification, sometimes comes on at unexpected times, and it cannot be turned off using the toggle in the operating system. Only the airplane mode hotkey can turn it off.

The following needs to be done:

• [x] Switch EC to use software hotkeys
• [ ] Release packages to support software airplane mode toggle
• [ ] Update kernel with driver to support touchpad lock, keyboard brightness, and airplane mode LED
• [ ] Potentially add support for software fan control