Make Elevator on Operator Real Command

[Java4First]

The current implementation works like the drive with a stick, but the control method is more like a button. Write a 'button' that implements this, and use real scheduled commands.

[Cal-Hagner]

I think this is resolved by #32
The control logic that the mechanical team requested matches this--and it seems to use "real scheduled commands" via a default manual control command (that reads off of the intake sticks) and a triggerable command (as part of FirePoseVision, triggered by the fire button)