Integrate with Payload

[Thomas-Neill]

We need to add some code to programmatically actuate the Payload servo from the commander node script. Probably we'll do this over MAVLink using the servo ports on the cube board.

Docs on MAVLink servo commands: https://ardupilot.org/dev/docs/mavlink-move-servo.html
Ozzy's Arduino code for actuating the servo: https://discordapp.com/channels/583083826092310529/1105931763932463104/1215436377248895078