MUONS: Zero-Field - Auto-Feedback IOC

[davidkeymer]

The current procedure is described here, along with a flowchart and further notes throughout the page.

Notes
The IOC will provide closed feedback control of the zero-field by continuously monitoring the magnetometer PVs (#4838) and adjusting the PSU currents accordingly.

Acceptance Criteria

• An IOC that will maintain the zero-field

[Tom-Willemsen]

Consider the case where pvs become disconnected at various points in the state machine.