refactors for compression + topk rw files for cifar

eval/run_xtimes_celeba_rw.sh

eval/step_configs/config_celeba_topKdpsgdRW.ini

eval/step_configs/config_celeba_topKdpsgdRWAsync.ini

eval/step_configs/config_celeba_topKdynamicGraph.ini

eval/step_configs/config_celeba_topKsharingAsyncRW.ini

src/decentralizepy/compression/Compression.py

src/decentralizepy/compression/Elias.py

src/decentralizepy/compression/Elias16f.py

src/decentralizepy/compression/EliasFpzip.py

src/decentralizepy/compression/EliasFpzipLossy.py

src/decentralizepy/compression/Lz4Wrapper.py