L2SS-358: Added APSCT and APSPU devices, their simulators. Added a common base image for the pypcc2 simulators. Separated station-dependend configs into separate CDB files. Added OPC-UA node path prefix to support instances with different paths to their nodes.

L2SS-391: Added StationControl device to control the lifecycle of the station (and potentially other top-level functionality)

L2SS-276: Initial implementation of XST device, made payload errors refer to FPGA they're from instead of which input they're for, and added subbands_calibrated flag to exposed SST parameters