FIND_DECAY and FIND_MCDECAY functor

Create two functor named FIND_DECAY and FIND_MC_DECAY that implements respectively the algorithms DecayFinder (new, see !3091 (merged)) and MCDecayFinder.

To be used in composition with other functors to get information about particles belonging to the decay chain.

FIND_DECAY (FIND_MC_DECAY) is MAP of _FIND_DECAY (_FIND_MC_DECAY), functor accepting const LHCb::Particle* (const LHCb::MCParticle*) or const LHCb::Particle& (const LHCb::MCParticle&) and returning a const LHCb::Particle* (const LHCb::MCParticle*).

TODO:

• Fix test;
• Adapt the functor to support MCParticles.

Perhaps related to issue: #356

Example in the DV MR DaVinci!781 (merged)

cc: @amathad

Phys/FunctorCore/tests/src/TestFunctors.cpp

@@ -2132,9 +2132,9 @@ BOOST_AUTO_TEST_CASE( test_decay_functor ) {
   auto df1_p     = df1.prepare( evtCtx, top_level );
   auto df2_p     = df2.prepare( evtCtx, top_level );
   auto df3_p     = df3.prepare( evtCtx, top_level );
-  auto df1_final = df1_p( in_parts );
-  auto df2_final = df2_p( in_parts );
-  auto df3_final = df3_p( in_parts );
+  auto df1_final = df1_p( true, in_parts );
+  auto df2_final = df2_p( true, in_parts );
+  auto df3_final = df3_p( true, in_parts );
 
   BOOST_CHECK( df1_final.has_value() && df1_final.value().size() == 1 );
   BOOST_CHECK( df2_final.has_value() && df2_final.value().size() == 1 );
@@ -2143,9 +2143,9 @@ BOOST_AUTO_TEST_CASE( test_decay_functor ) {
   auto const chain1   = Functors::chain( Functors::Functional::ValueOr{0}, PT, Functors::Functional::Front{}, df1 );
   auto const chain1_p = chain1.prepare( evtCtx, top_level );
   auto const chain2   = Functors::chain( Functors::Functional::ValueOr{0}, PT, Functors::Functional::Front{}, df2 );
-  auto const chain2_p = chain1.prepare( evtCtx, top_level );
+  auto const chain2_p = chain2.prepare( evtCtx, top_level );
   auto const chain3   = Functors::chain( Functors::Functional::ValueOr{0}, PT, Functors::Functional::Front{}, df3 );
-  auto const chain3_p = chain1.prepare( evtCtx, top_level );
+  auto const chain3_p = chain3.prepare( evtCtx, top_level );
   auto       pt1      = chain1_p( true, in_parts );
   auto       pt2      = chain2_p( true, in_parts );
   auto       pt3      = chain3_p( true, in_parts );