make qkdg local finitie elements work with functions that provide no callable
requested to merge liesel.schumacher/dune-pdelab:bugfix/support-functions-with-evaluate-in-lfe into releases/2.7
Some functions like Dune::VirtualFunction from dune/common/function.hh only provide an evaluate method and no callable. To make the dg local finite element methods compatible with these we use makeFunctionWithCallOperator from dune-localfunctions in the same way it is done for the local finite elements in dune-localfuntions. If the function already has a callable it only gets forwarded.