make_flux_sparsity_pattern with flux couplings on a subset of the faces

make_flux_sparsity_pattern with flux couplings on a subset of the faces

Add an optional std::function input parameter to
make_flux_sparsity_pattern which describe over which faces there should
be flux couplings in the created sparsity pattern.

internal::make_flux_sparsity_pattern has one implementation for a
generic DoFHandlerType and a specialization for hp::DoFHandler. To
circument a bug where MSVC can't deduce which of these internal
functions should be called, change DoFHandlerType to
dealii::DoFHandler in the generic function.

To avoid another bug where MSVC can't construct a templated class,
call one of the overloaded versions of make_flux_sparsity_pattern with
always_couple_on_faces (even if this is already the default value).