Reorganization of Phase2 DQM

As proposed by Ian in his talk, the DQM & Validation plugins for L1 track trigger are to be moved from SiOuterTracker to SiTrackerPhase2. Top level DQM folders are also renamed accordingly.

[x] Migrate the plugins PR
[x] Verify that the content of the histograms remains the same.
[ ] Delete the packages DQM/SiOuterTracker & Validation/SiOutertrackerV
[ ] Phase2 validators need to be informed about the changes.
[ ] Follow up with L1T DQM about further improvements, some points are described in the talk.

FYI @lapertosa @mdelcourt @emiglior

CMSTrackerDPG / Tasks

Reorganization of Phase2 DQM #20