Draft: HID: bpf: Add Huion KDial Mini K20
The device is nice enough to report each button press with a different keyboard key.
The events are split on 3 different report IDs, so we need to regroup them into just one so userspace sees only one consistent device.
Fixes #35
Again, we probably want to keep this in testing until the userspace part is ready (libwacom/libinput/gnome/KDE)
Also marking as draft because having some tests would be useful.