nodes: Remove unneeded make_child_impl overloads
nodes: Remove unneeded make_child_impl overloads

By filling node_args already in make_child/make_child_named, it is
possible to dispatch to only two make_child_impl methods - one for
owning nodes and another for leaf nodes. This greatly reduces the number
of methods we have.

CasparKielwein/flexcore,FlexCoreLib/flexcore