add closestToBeamState() accessor to `v2::Track` skin
Allows closestToBeamState()
to be called on proxies used to iterate over SOA::Container
s of v2::Track
.
This is needed for Moore!219 (merged) to be compatible with Rec!1659 (merged), which changed the ipchi2 calculation to rely on closestToBeamState()
.
See also the discussion on Moore!223 (comment 2799900).
Edited by Marco Cattaneo