Improvements for QA function of CbmSeedFinderSlidingWindow

-The QA functionality of CbmSeedFinderSlidingWindow is now encapsulated in a separate class CbmSeedFinderQa.

-Histograms and a summary canvas were added to this class for visualization.

-The time offset between triggers and MC event times are now computed and stored in a histogram.

Contains all commits from !690 (merged)

Update:

-A constant offset which is applied to all trigger times can now be set.

@v.friese