[ATR-22206] Change InputMaker merging code to be typeless
This MR changes matchDecision
from a templated function on the link CONTAINER
type, to a typeless function which manipulates type data via the type's CLID.
This resolves a limitation where a user needing to use m_mergeUsingFeature
could only do so if their slice's feature inherited from xAOD::IParticle
. This limitation is now gone.
Note: I am getting a linker error against the typelessfindLinks
function which I don't understand. Running CI to check if it's just me.