Sweeping !20024 from 21.3 to master. Adding MM and STGC clusterization packages for the NSW, with interfaces and example tools

Adding MM and STGC clusterization packages for the NSW, with interfaces and example tools

See merge request !20024 (merged)

Adding original author @rosati as watcher.

This merge request affects 2 packages:

• MuonSpectrometer/MuonReconstruction/MuonDataPrep/MMClusterization
• MuonSpectrometer/MuonReconstruction/MuonDataPrep/STgcClusterization

Adding @rosati ,@wleight as watchers

added MuonSpectrometer master review-pending-level-1 labels

CI Result SUCCESS

	Athena	AthSimulation
externals
cmake
make
required tests
optional tests

Full details available at NICOS MR-20208-2019-01-08-07-37
Athena: number of compilation errors 0, warnings 0
AthSimulation: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST 31977] (for remote access see the FAQ for MR reviewers)

added review-approved label and removed review-pending-level-1 label

merged

mentioned in commit 08ec5ba9

added sweep:ignore label