Add parent ghost tracks to ftag deriations

We might do a better job tagging large-R jets if we had the ungroomed ghost associated tracks. Unfortunately we weren't saving these anywhere, so I'm adding them to FTAG1 and FTAG2. Should unblock atlas-flavor-tagging-tools/training-dataset-dumper!757 when we get new derivations.

Attention @ligang, @bdong, @robouque