Gas gain slicing: allow multiple approaches in database, keep info

[Vindaar]

Instead of overwriting the dataset stored for the center chip of a detector in the InGrid database when re-computing the "gas gain vs energy calibration factor" fit, we should store each different approach (described by the enum (needs to be extended to "old default way"):

  GasGainVsChargeCalibKind = enum
    gcMean, gcIndividualFits

as an individual dataset in the database.

Then when computing the energy from charge, we should read from the config.toml file, which parameters to use and store in the resulting energyFromCharge dataset, which way was used (in addition to the parameters? No parameters cannot be stored, because they vary possibly for each cluster once we have linear interpolation between different runs in place).