Draft: Move reco algorithms and standard particles in a common location

Code from Hlt2Conf and RecoConf is copied into Phys/DaVinci but is dangerous as it might diverge. In order to avoid code duplication and make easier its maintenance some scripts are moved in a dedicated package in Rec.

Address Moore#372 (closed). Related to the gran task: https://gitlab.cern.ch/lhcb-dpa/project/-/issues/180

FYI: @graven, @nskidmor, @sstahl

To be merged with DaVinci!700 (merged) and Moore!.

Depends on the decision in #353 (closed).