Handling of AMI tags in xAODskimming

Currently, we simply include the longest common substring including the DSID from the input file names in the output file names. In most cases (at least for PxAODs) this causes the AMI tags to be carried over as desired. It has come to attention, though, that one can encounter cases where some parts of a DSID have one and some have two "e" tags such that after the first "e" tag the file names already diverge and the (for practical purposes) most important "s" (or "a") tag is not carried over.

-> find and implement a solution to reliably carry over a/s tags (better: all AMI tags)