introduce a new set of ASG test files (ATLASG-1636)

This is now an extended set of files to cover the different kinds of files we may use as input in analysis.

I did fix up relevant tests as far as I could, but had to disable the electron-DNN tests temporarily, as that is apparently not supported on DAOD_PHYS (yet).

This contains a fix to e-gamma tools which avoids an endless recursion in some cases, and avoids repeated look-ups of the EventContext at the same.

This is needed in 22.0 (as well as master), as we have tests/MRs in 22.0 that fail because the current input files are too old.