Handle CAF making when Pandora runs after the NuGraph2 filter

[rtriozzi]

This PR adds a mode governed by the UsePandoraAfterNuGraph FHiCL flag to handle NuGraph2 variables in the CAF maker, when using a second-pass Pandora after filtering noise with NuGraph2, based on work by summer intern Leonardo Lena.

This PR also provides code to fill new NuGraph2 slice-level variables in CAF files.

Relevant information about the NuGraph2 chain is provided in icaruscode PR #868.

---

Associated PRs

• Add more NuGraph2 variables to CAFs sbnanaobj#183
• Introduce multi-slice NuGraph2 inference and filtering icaruscode#868

---

Review

Tagging for review @acampani and @PetrilloAtWork as reconstruction and infrastructure experts. Thanks a lot!

---

Description

Please provide a detailed description of the changes this pull request introduces. If available, also link to a docdb link where the issue/change have been presented on/discussed.

• Have you added a label? (bug/enhancement/physics etc.)
• Have you assigned at least 1 reviewer?
• [] Is this PR related to an open issue / project?
• Does this PR affect CAF data format? If so, please assign a CAF maintainer as additional reviewer.
• Does this PR require merging another PR in a different repository (such as sbnanobj/sbnobj etc.)? If so, please link it in the description.
• Are you submitting this PR on behalf of someone else who made the code changes? If so, please mention them in the description.

[cerati]

Thanks, overall it looks great -- especially removing the need for the hit mapping makes things much simpler.

The two things I would suggest to change are:

1. Avoid erasing elements from vectors. I think it should be much easier to simply add a check that the element is non-null in the Fill*NuGraph method. Or is there another reason for erasing the elements with null nugraph score?
2. There is no need to get the NuGraph slices from the event if then we just use slices (when UsePandoraAfterNuGraph=true)

[rtriozzi]

I have addressed Giuseppe’s comments (with which I agree). I also added more code to fill some new NuGraph2 CAF variables we developed. I opened the corresponding sbnanaobj PR #183.