PyUtils: Enable flake8 for scripts and make them compliant

Tools/PyUtils/CMakeLists.txt

Tools/PyUtils/bin/checkMetaSG.py

Tools/PyUtils/bin/checkPlugins.py

Tools/PyUtils/bin/checkxAOD.py

Tools/PyUtils/bin/diff-athfile

Tools/PyUtils/bin/diff-jobo-cfg.py

Tools/PyUtils/bin/diffConfigs.py

Tools/PyUtils/bin/diffPoolFiles.py

Tools/PyUtils/bin/dlldep.py

Tools/PyUtils/bin/dump-athfile.py

Tools/PyUtils/bin/dumpAthfilelite.py

Tools/PyUtils/bin/filter-and-merge-d3pd.py

Tools/PyUtils/bin/getMetadata.py

Tools/PyUtils/bin/gprof2dot

Tools/PyUtils/bin/issues

Tools/PyUtils/bin/magnifyPoolFile.py

Tools/PyUtils/bin/merge-poolfiles.py

Tools/PyUtils/bin/meta-reader.py

Tools/PyUtils/bin/pool_extractFileIdentifier.py

Tools/PyUtils/bin/pool_insertFileToCatalog.py