Cabinet Banks - Implement power sequencing and investigate COTS control

Change of focus - late PI23...

It became apparent once the stub device was implemented that rather than orchestrating power control from the top level repo we should introduce further choreography elements into the Spshw devices which are requiring power, akin to the way that e.g. tiles request power from their subrack. This will produce a more homogenous solution and will be better in the long run. Therefore we are stepping back from further development of the CabinetBank device in this PI and will focus instead on designing the architecture.

• Propose an architecture for the new power control elements.
• Discuss the proposals in a workshop and decide how to proceed.
• Give a "demonstration" which explains the plans to stakeholders.

The original description:

• Complete implementation of Cabinet Bank device to orchestrate power sequencing for banks of 3 cabinets.
• Early in PI23: Generate a list of all the COTS devices in the SPS cabinets and determine what the control system requires of them. Search for existing Tango devices with help from the Wombat team if needed. 
• Second half of PI23: Wombat team to start designing/developing any missing devices.
• Investigate where the device servers fit in the MCCS architecture and plan the work needed to integrate them with MCCS.