Extend Yukon service to activate and control servo motors

[dannystaple]

Extend the Yukon service #25 to support up to 4 servo motors. These will be attached to one slot of the Yukon, determined in the service for now.

Topics:

• /servomotors/position: index, angle -> move the servo motor to the intended angle in degrees
• /servomotors/detach: [index] -> Detach servo motors (stop driving them). All if no index is provided.

Behaviour:

• Detach all servo motors in the stop method, if there's no contact for a second.

A simple phone app screen could be set up to test servo motors with angle + number sliders, and detach buttons. The back button will send detach all.

Definition of ready

• Create the yukon service with motors topics #25 Yukon service
• Convert phone app to multi page #35

Definition of done

• Yukon topics created
• Phone app screen created
• Tested with a few loose servo motors
• PR merged supporting servo motors