* Introduce proper generator IDs

* 3 values
  * global ID assigend to a o2::eventgen::PrimaryGenerator
  * cocktail constituent ID in case a o2::eventgen::Generator consists
    of multiple cocktail constituents. If a specific constituent is used
    for an event, that event will be flagged with that ID
  * source ID to mark source in emebdding scenarios

* all 3 values are encoded into a single short, passed to mcCollision
  table at the end

* provide decoding via helper functions/dynamic columns in mcCOllision
  table

Set the IDs
  * Global ID (and short description)
    * can be set via
      o2-sim --confKeyValues \
       "PrimaryGenerator.id=3;PrimaryGenerator.description=a specific gen"

  * Each cocktail constituent must first be registered via
    o2::eventgen::Generator::addCocktailConstituent(int, std::string)

    then, each egnerated event must set a valid ID during
    o2::eventgen::Generator::GenerateEvent
    or
    o2::eventgen::Generator::importParticles

    if cocktail constituents are set but no valid ID is given, no event
    will be generated

  * source ID is derived by the framework as before,  not up to the user

* combine MC Gen ID and particle status to MCGenProperties
  (naming not final, MCGenHelper, MCGenUtils?)

Please consider the following formatting changes

* Be consistent with Run1 and Run2

* rename cocktail to subGenerator everywhere

* a cocktail should stay a cocktail of different generators

* remove comment in AnalysisDataModel

* Adjust ID ranges

* generator ID from 0 to 127 (included)
* sub-generator ID from -1 to 30 (included)
* source ID from 0 to 15 (included)

---------

Co-authored-by: Benedikt Volkel <benedikt.volkel@cern.ch>