Method Class_Version() must be both 'static' and 'public'

genreflex is producing at least two errors while compiling CMSSW
with

    method Class_Version() must be both 'static' and 'public'.

for class reco::LeafRefCandidateT.

Move Class_Version() from protected to public to meet Reflex
requirements.

```
--->> genreflex: ERROR: class reco::LeafRefCandidateT<edm::Ref<std::vector<reco::PFCluster>,reco::PFCluster,edm::refhelper::FindUsingAdvance<std::vector<reco::PFCluster>,reco::PFCluster> > >'s method Class_Version() must be both 'static' and 'public'.
--->> genreflex: ERROR: class reco::LeafRefCandidateT<edm::Ref<std::vector<reco::Track>,reco::Track,edm::refhelper::FindUsingAdvance<std::vector<reco::Track>,reco::Track> > >'s method Class_Version() must be both 'static' and 'public'.
```

Signed-off-by: David Abdurachmanov <David.Abdurachmanov@cern.ch>