Draft: cmd/uncertainty: handle supplemental GPR based on arm power
The CAL_SUPPLEMENTAL_GPR env var, if specified, will trigger the uncertainty calculation to search the directory path specified in the env var for a supplemental GPR file to be applied to the current uncertainty calculation based on current arm power.
This implementation expects supplemental GPR files with names formatted as such:
<IFO>_supplemental_gpr_<PWR>_watts.hdf5
where <PWR>
is the relevant arm power. The included logic picks the GPR whose specified power level is closest to the current power level (average of the two arms).
This patch requires the DARMUncertainty.compute_response_uncertainty() method be modified to take an additional supplemental_gpr
keyword argument specifying the path to an HDF5 GPR file to be included in the calculation.