add NtupleSvc basketsize property and forward in RCWNTupleCnv Branch creation

The goal of the change is to be able to control the basketsize call in RCWNTupleCnv.cpp by configuring the NTupleSvc property. It has been observed that for most use cases of FunTuple controlling the basket size can reduce significantly by more than 30-40% the memory consumption in case many TTrees are created in a single job. More tests will be documented here.

Since RCWNTupleCnv has as private a INTupleSvc, a new virtual function is defined for INTupleSvc

FYI: @clemenci , @sponce , let me know if this is what you had in mind as change and if the target branch is fine.

MR is in draft , since i am testing changes in LHCb to be sure this can be controlled from option file.

Comes together with lhcb/LHCb!4697 (merged)