Add deduction guides for readers and writers

dune/vtk/CMakeLists.txt

dune/vtk/test/CMakeLists.txt

dune/vtk/test/checkvtkfile.hh

dune/vtk/test/test-typededuction.cc

dune/vtk/test/test-vtkwriter.cc

dune/vtk/vtkreader.hh

dune/vtk/vtkwriter.hh

dune/vtk/writers/CMakeLists.txt

dune/vtk/writers/vtkimagedatawriter.hh

dune/vtk/writers/vtkrectilineargridwriter.hh

dune/vtk/writers/vtkstructuredgridwriter.hh

dune/vtk/writers/vtkunstructuredgridwriter.hh