Finished implementing vertex DoF ghost-layers required for facet integrals...

Finished implementing vertex DoF ghost-layers required for facet integrals with coupling into neighboring macros. This feature is for example relevant for the P1CG x enriched Galerkin coupling (P1 -> P0).

Tested for vector Laplace problem on unit square in P1DGEConvergenceTests2D.cpp.
31 jobs for kohl/stokes-eg-macro-coupling in 55 minutes and 41 seconds (queued for 2 seconds)
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Name Stage Failure
failed
clang_13.0_mpionly_eigen_petsc_trilinos Pretest
            midpoint[d] += affineElementVertices[i][d] / 3.;
~~~~~~~~~~~~~~~~~~~~~ ^
1 error generated.
make[2]: *** [src/hyteg/CMakeFiles/hyteg.dir/build.make:18315: src/hyteg/CMakeFiles/hyteg.dir/p1dgefunctionspace/P1DGEFunction.cpp.o] Error 1
make[2]: *** Waiting for unfinished jobs....
make[1]: *** [CMakeFiles/Makefile2:20953: src/hyteg/CMakeFiles/hyteg.dir/all] Error 2
make: *** [Makefile:141: all] Error 2
Cleaning up project directory and file based variables
ERROR: Job failed: exit code 1