AssoByHits with GEM hits porting 8XY

[calabria]

This PR contains the new module needed to associate the GEM tracking recHits (GEMHitAssociator) and the all the changes needed in the AssociatorByHits to make it associate also GEM tracking recHits. The association of GEM hits is disabled by default to avoid problems when the GEM detectors are not present in the geometry scenario. Moreover a new plot representing the averange number of GEM tracking recHits vs eta hs been added in the MuonTrackValidator. It is not filled by default, it has to be switched on when GEM detectors are present in the simulation. I checked the code with the following runTheMatrix command and all tests ended successfully: runTheMatrix.py -l limited -i all (with the use of GEM disabled, but I tested it also with GEM hits present and GEM association enabled without problems).

Same content as #11962 in 76X.

[cmsbuild]

A new Pull Request was created by @calabria (Cesare) for CMSSW_8_0_X.

It involves the following packages:

SimMuon/MCTruth
Validation/RecoMuon

@civanch, @danduggan, @mdhildreth, @cmsbuild, @deguio, @vanbesien, @davidlange6 can you please review it and eventually sign? Thanks.
@rociovilar, @abbiendi, @trocino, @jhgoh, @battibass this is something you requested to watch as well.

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[civanch]

please test

[cmsbuild]

The tests are being triggered in jenkins.
https://cmssdt.cern.ch/jenkins/job/ib-any-integration/9679/console
https://cmssdt.cern.ch/jenkins/job/ib-any-integration/9680/console

[cmsbuild]

+1
Tested at: 81a7ccc
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-12382/9680/summary.html

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-12382/9680/summary.html

[civanch]

+1

[calabria]

@deguio @Degano @davidlange6 can this PR be approved and merged? thanks

[deguio]

+1

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_8_0_X IBs (tests are also fine). This pull request requires discussion in the ORP meeting before it's merged. @slava77, @davidlange6, @Degano, @smuzaffar

[davidlange6]

+1