[PWGLF] Added MC truth matching for nSigmaTPC histograms

[tonmoySh]

This pull request implements a MC truth-matched NSigma TPC histogram for pions, kaons and protons in the Nuspex Task. The aim is to study the PID contamination, by comparing the reconstructed tracks with the true MC matched particle identity.
Key changes:

1. Added "processTrackMCLabels" function to fill histograms using MC truth labels.
2. Added a 2dim std::array to manage 18 particle species across 3 selection categories (pi,K, p).
3. Initialised the histogram registry for storing these new histograms in a structured output (test_mclabels/nsigmatpc).

[github-actions]

O2 linter results: ❌ 135 errors, ⚠️ 15 warnings, 🔕 0 disabled

[maciacco]

@tonmoySh this isn't directly related to your PR, but it would be great to check the linter errors on PDG codes in the future