23.0-cleanup-PixelCalibAlgs

Addressing ATLASRECTS-7542, this MR puts the mapping in a comma separated value file and introduces a unit test on the mapping function. A separate python script with functions parsing the same file was introduced; legacy python parsing functions were also left there to enable one-to-one comparison of new and old versions. The changes are then propagated to the c++ code, the ROOT macros and the python scripts. (Previously, the python had attempted parsing of c++ header files to obtain the mapping which is error prone in the face of minor format changes.)