MVADictTools - Import keras support code
Rec!1894 (merged) removes from Rec/ChargedProtoANNPID
all legacy run 1 and 2 MVAs, including a bunch of support code for yPID variables, including keras models. This code really should never have been in this package in the first place and instead should have been added to an LCG release and used from there.
This MR (temporarily) fixes MVADictTools to not rely on the (should have been private) implementation linker library in Rec/ChargedProtoANNPID
by just adding the keras code to a new package producing a linker library in Phys.
Longer term, if this is still required for Run III, it should be removed from Phys again and instead used from where it should have been in the first place, which is an external package from the LCG release area.
Goes together with Rec!1894 (merged)