Implemented local refinement

apps/benchmarks/NonUniformGridGPU/GridGeneration.h

apps/benchmarks/NonUniformGridGPU/LdcSetup.h

apps/benchmarks/NonUniformGridGPU/NonUniformGridGPU.cpp

apps/benchmarks/NonUniformGridGPU/NonUniformGridGPU.py

...s/NonUniformGridGPU/simulation_setup/benchmark_configs.py

python/lbmpy_walberla/packing_kernels.py

...lbmpy_walberla/templates/LbmStorageSpecification.tmpl.cpp

...n/lbmpy_walberla/templates/LbmStorageSpecification.tmpl.h

python/pystencils_walberla/jinja_filters.py

python/pystencils_walberla/kernel_selection.py

src/gpu/communication/NonUniformGPUScheme.h

src/lbm_generated/gpu/NonuniformGeneratedGPUPdfPackInfo.h

...bm_generated/gpu/NonuniformGeneratedGPUPdfPackInfo.impl.h