Change F.CLOSESTTOBEAM functor such that it does not take any arguments and can be used in composition

Following a mattermost discussion to get the position of the track closest to beam one currently has to do

F.CLOSESTTOBEAM(F.POSITION) @ F.TRACK

but we want to instead do:

F.POSITION @ F.CLOSESTTOBEAM @F.STATES @ F.TRACK

Requires simply removing argument support for CLOSESTTOBEAM functor.

FYI: @mstahl , @sstahl , @graven