Externals Update, master branch (2021.02.03.)

Upgraded all projects to atlasexternals-2.0.98. The list of changes wrt. atlasexternals-2.0.97 is (atlasexternals@2.0.97...2.0.98):

• Removed the installation of the compiled bytecode files for python modules (thanks to @fwinkl);
• Multiple updates to FindGeant4.cmake;
  • Made it set a number of more environment variables, as required by Geant4 10.6 (thanks to @bmorgan);
  • Made it possible to pick up the G4 data files from somewhere other than the hardcoded AFS path during build (needed for ATLINFR-3946);
• Updated lwtnn to version 2.11.1 (thanks to @dguest);
  • Had to make a small update in Reconstruction/LwtnnUtils to make it compatible with the new version;
• Updated FindGaudi.cmake not to "re-run" in a given context on multiple calls (thanks to @fwinkl);
• Multiple updates to CheckerGccPlugins (thanks to @ssnyder);

The update should not need full-build. So let's see how it does without it...