Mask detectors in POLDI data automatically

[MichaelWedel]

This addresses #11607.

PoldiLoadRuns now optionally (it's the new default behavior) excludes detectors that deviate too much (most often because of gamma background) from the rest. It's essentially an additional call to MedianDetectorTest. The change is documented in the algorithm documentation.

Testing information
Code review. You could run the following script with varying parameters to see that the number of masked spectra changes (by using Color fill plot for example):

# Only the first 6 and the last 6 spectra are 0
idfMask = PoldiLoadRuns(2013, 6903, 6904, 2, MaskBadDetectors=False)

# Masking with default parameters excludes the very intense spectra around spectrum 320 and some others inbetween.
autoMask = PoldiLoadRuns(2013, 6903, 6904, 2)

# Setting the threshold higher leads to fewer detectors being masked
fewerMasked = PoldiLoadRuns(2013, 6903, 6904, 2, BadDetectorThreshold=5.0)

# The opposite happens for lower thresholds
moreMasked = PoldiLoadRuns(2013, 6903, 6904, 2, BadDetectorThreshold=1.5)

[FedeMPouzols]

All looks good and explained in the docs. Automated tests pass and from manual tests it seems to behave well, as I can see the increasing number of (masked) horizontal lines in the color plots.