Fix the fallout of introducing AODFix infrastructure
This MR fixes the problems arising with !56735 (merged):
- Use try/except to catch import-errors in project other than Athena. If AODFix needs to be applied by AthAnalysis we need to move the AODFix code to another package.
- Add some python logic to deal with the AODFixVersion metadata beeing either a string or a list of strings. Reading the old AOD-Fix code, I don't understand how we ended up with a list-of-strings in the metadata of
/cvmfs/atlas-nightlies.cern.ch/repo/data/data-art/aod/AOD-20.7.9.9/AOD-20.7.9.9-full.pool.root