Prepare online spectra for FrsSci data versus Musli data

[audreychatillon]

still on-going

2D histos to get on-line correlation between FrsSciCal vs (MusliCal and MusliHit)

Describe your proposal.

Mention any issue this PR is resolved or is related to.

---

Checklist:

• [x] Rebased against dev branch
• [x] My name is in the resp. CONTRIBUTORS/AUTHORS file
• [x] Followed the pull request guidlines and the Git workflow
• [x] Followed the seven rules of great commit messages