New DecayFinder for Run 3

This MR contains a new templated DecayFinder.

TODO:

• Preliminary design of the DecayFinder for V1 Particles. It contains:
  • Class Decay::Node
  • Class Decay::Arrow
  • Class Decay::Tree
  • Class Decay::DecayFinder
  • Interface IDecayFinder.
• Convert tests from main.cpp into set of pytest.
• Introduce dependency of FunTuple on finder. (Analysis!916 (merged)).

Adapt methods for V2 Particles: This will be a follow-up MR issue (#398)

To be tested with: Analysis!916 (merged)

FYI: @erodrigu and @pkoppenb