Change TrMINIPCHI2 functors to accept v2 vertices
Changes the input vertex container type to the TrMINIPCHI2 functor from a vector of LHCb::RecVertex to a vector of LHCb::Event::v2::RecVertex.
This is needed to run the upgrade HLT1 cleanly.
It's ugly because it mixes Track v1 functors with v2 vertices. But, the upgrade studies are the only customers of this functor, so 'breaking' it in this way is arguably not completely awful.