canbus: Add CMD_QUERY_UNASSIGNED extended response, enabling query response after id assignment

[kageurufu]

msg=[0x00] responds with a klipper-compatible response

• Response is [0x20, canbus_uuid, app_id] (0x01 for klipper, 0x11 for Canboot)

msg=[0x00, 0x01] enables extended responses.

• "Normal" Klipper devices will ignore this extended bit completely
• Danger-Klipper devices will now respond regardless of whether the device is already assigned a node_id. Responses are generally klipper-compatible, although in the odd case that someone manually sends [0x00, 0x01] from Klipper, the app_name will probably show as "Unknown", unless it happens to be 0x01 or 0x11. If the device is already assigned, the response will be ignored completely
  • Response: [0x20, canbus_uuid, 0x07] 0x07 being a new Danger-Klipper app_id
  • Response: [0x21, canbus_uuid, node_id] 0x21 is a new "RESP_HAVE_NODEID" value

This also updates scripts/canbus_query.py to use the extended query, now listing Found canbus_uuid=%012x, Application: Danger-Klipper, Unassigned Found canbus_uuid=%012x, Application: Danger-Klipper, Assigned: 05

Checklist

• [x] pr title makes sense
• [x] squashed to 1 commit
• [ ] added a test case if possible
  • [x] Tested over U2C
  • [x] Tested with Can-Bridge
• [ ] if new feature, added to the readme
• [ ] ci is happy and green