Draft: e-tag dataset and parser tool

Following the discussion in ATEAM-787 and core-sw meeting, I created a .csv dataset and a parsing tool for e-tags. The dataset is created from the PMG TWiki page: https://twiki.cern.ch/twiki/bin/view/AtlasProtected/PmgMcSoftware.

The tool return a map<string, string> object given an e-tag string with the information from the TWiki page. This can be coupled with the info from the in-file metadata to find out the specific version of the MC generator software (e.g. Sherpa version). The tool has both a python and a C++ interface.

Currently the tool has no clients, but in the future it can be used to update the in-file metadata e.g. at the start of derivation jobs. Example usage via CLI:

> e-tag-parser.py e8276
EvtGen         : 1.7.0
HepMC          : 2.6.11
Herwig7        : 7.2.1
Lhapdf         : 6.2.3
MadGraph       : 2.8.1.atlas7
Powheg ATLAS   : 00-04-05
Pythia8        : 8.244
Release        : 21.6.53
Rivet          : 3.1.2
Sherpa         : 2.2.10p5
Starlight      : r313
Superchic      : 3.0.6
e-tag          : e8276

Adding @tadej @cgutscho @mgignac and please add anyone else who might be interested.