[PWGLF,PWGMM] add mftReassociationValidation.cxx task

[AlexianL]

Add the mftReassociationValidation.cxx task with the goal of estimating the efficiency of MFT tracks DCA reassociation methods.

processMcReassociation3d as an example :

• I loop over all tracks in the BestCollisionsFwd3d table (reassociated3dMftTrack)

• I get the original track info by templating : auto templatedTrack = reassociated2dMftTrack.template mfttrack_as();

• I check only tracks who have a MC particle (these MC particle are obtained by templating the tracks as McParticle
  auto particle = templatedTrack.template mcParticle_asaod::McParticles();)

• I separate ambiguous and non-ambiguous track through : if (reassociated2dMftTrack.ambDegree() > 1) { // AMBIGUOUS TRACKS

• For all ambiguous tracks, I check whether the collision with which it is associated to mcCollisionId() corresponds with the MC particle associated to the same track mcCollisionId() : if (collision.mcCollisionId() == particle.mcCollisionId()) {

• Then for ambiguous tracks only, I check whether the track was reassociated (or not) to a new collision using the 3D reassociation method : if (templatedTrack.collisionId() == reassociated2dMftTrack.bestCollisionId()) { // IS NOT 2D REASSOCIATED

• For both reassociated tracks (which have bestCollisionId different than collisionId) and not reassociated tracks (which have bestCollisionId == collisionId) I have to obtain the information of the reassociated (or not) collision through a hash table. This is done in the "processCreateLookupTable" function, where I store the posX, posY, posZ and mcCollisionId of all collisions. Then back to processMcReassociation3d, I get these informations back by searching for the BestCollisionId in this hash table. In the end, I get the mcCollisionId of the collision corresponding to BestCollisionId through : const int mcCollisionIdReco = iteratorRecoMcCollisionId->second;

• Once this information is retrieve, I can check whether the collision with which it is associated to mcCollisionId() corresponds with the MC particle associated to the same track mcCollisionId() : if (mcCollisionIdReco == particle.mcCollisionId()) {

• If the track is non-ambiguous (= associated in time with only one collision), I check whether the collision with which it is associated to mcCollisionId() corresponds with the MC particle associated to the same track mcCollisionId() : if (collision.mcCollisionId() == particle.mcCollisionId()) {