Stop using Q1NodalBasis within PortableGreyMap and PortablePixelMap
Use LagrangeBasis from dune-function instead.
Needs https://gitlab.dune-project.org/staging/dune-functions/-/merge_requests/387
Use LagrangeBasis from dune-function instead.
Needs https://gitlab.dune-project.org/staging/dune-functions/-/merge_requests/387