Run all configurations at once

See merge request abrusamo/pftruth-standalone!11

SimClusterMerger and ID assignment tests

See merge request abrusamo/pftruth-standalone!10

Re-work unit testing

See merge request abrusamo/pftruth-standalone!9

[load-from-root] Run merging from COCOA ROOT files and testing

See merge request abrusamo/pftruth-standalone!8

Now the all the test are in header files and only PFTruthTests.cc
contains the Catch2 main to avoid linking issues.

Add members for saving mergedShowers and add the possibility of running
the merging starting from multiple ROOT files.

Add SimShower header files. Since SimShowers are the same object as
SimClusters, the file only contains typedefs.

Hits cached position

See merge request abrusamo/pftruth-standalone!7

Speed up event merging step

See merge request abrusamo/pftruth-standalone!6

Automated sample generation

See merge request abrusamo/pftruth-standalone!5

PFParticles and two-stage merging

See merge request abrusamo/pftruth-standalone!4

Add plots for truth information and move to el9

See merge request abrusamo/pftruth-standalone!2