Is it possible to send disarm code via MQTT?
I am successfully running the Arduino HomeAssistant-MQTT.ino example with Home Assistant (HA). For the life of me I cannot figure out how to force the HA alarm keypad to send a user code to disarm the system. If I hard code a user code into the sketch, compile, and upload to the Arduino, I can enter any number into the HA keypad to disarm the system. Even a single digit works.

I would like the HA alarm keypad to just pass the user code via MQTT to the Arduino, which then passes the code to the alarm panel. What am I missing?

HA config:
```
mqtt:
  alarm_control_panel:
    - name: Alarm Partition 1
      state_topic: dsc/Get/Partition1
      command_topic: dsc/Set
      availability:
        topic: dsc/Status
      code: REMOTE_CODE
      payload_disarm: 1D
      payload_arm_home: 1S
      payload_arm_away: 1A
      payload_arm_night: 1N

  binary_sensor:
    - name: Security Trouble
      state_topic: dsc/Get/Trouble
      device_class: problem
      payload_on: 1
      payload_off: 0

    - name: Front Door
      state_topic: dsc/Get/Zone1
      device_class: door
      payload_on: 1
      payload_off: 0

    - name: Down Front Bedroom Window
      state_topic: dsc/Get/Zone2
      device_class: window
      payload_on: 1
      payload_off: 0
...
```