Stop using Dune::VirtualFunction interface

This MR should switch dune-fufem from the deprecated Dune::VirtualFunction-based function interface to the new one from dune-functions. To this end it will

• introduce the necessary utilities for the interface switch,
• switch the used function interface from Dune::VirtualFunction and VirtualGridFunction to std::function and Dune::Functions::Grid(View)Function,
• not take care for backward compatibility, so you have to adjust your user code,
• remove all function implementations of the old function interface.

The following tests lead to a deprecation warning and indicate that some code has to be adjusted:

• adolctest
• basisgridfunctiontest
• basisinterpolatortest
• coarsegridfunctionwrappertest
• functionintegratortest
• generalizedlaplaceassemblertest
• gradientassemblertest
• gridfunctionadaptortest
• gridfunctiontest
• h1functionalassemblertest
• newpfeassemblertest
• pgmtest
• ppmtest
• secondorderassemblertest
• subgridxyfunctionalassemblertest
• vintagebasisgridfunctiontest

Further tasks:

• Provide helper utilities to create local functions in assemblers, since dune-fufem's local assemblers are not aware of the GridView type.
• Remove some old function classes, that are no longer needed.
  • LocalBasisDerivativeFunction
  • LocalBasisJacobianFunction
  • AlienElementLocalBasisFunction
  • CachedComponentWrapper