HID: bpf: Add support for the Huion KeyDial K20 over bluetooth

When connected over bluetooth this device is just different enough that
forcing it into the same source file as the USB connection doesn't gain
us much benefit. So let's duplicate this.

Code and tests originally produced by Claude code.

Link: https://gitlab.freedesktop.org/libevdev/udev-hid-bpf/-/work_items/69
Link: https://gitlab.freedesktop.org/libevdev/udev-hid-bpf/-/merge_requests/201
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
Signed-off-by: Jiri Kosina <jkosina@suse.com>

Author: Benjamin Tissoires