To aid in commissioning and characterization tasks, DET requested to revive the slopes_ff_from_file argument present from before the introduction of the CalibrationData (v1) API.
This MR is the first part adding a new implementation (now called slopes_ff_from_path to support both file and directories, more details below) for this. As referring to constants from arbitrary paths has the potential to break reproducibility, there will be two more parts following:
Enforce the use of --non-reproducible in xfel-calibrate when changing this parameter
Special commissioning for non-user proposals causing the webservice to include --non-reproducible in the argument list and piping output to scratch rather than proc
The slopes_ff_from_path parameter may point to a file or directory:
If a file, multiple PDUs and calibration may be overriden from it. This is the local output mode of the current AGIPD FF notebook and implemented as legacy mode.
If a directory, expect files named according to the local output of dark notebooks (const_{calibration}_{pdu}.h5) and override accordingly. This is requested by DET to be used going forward.
