Draft: Modernize the MS vertex finding algorithm

Modernisation changes:

• Using smart pointers
• Changing to range-based for loops where possible
• Adding Gaudi properties
• Using standard ATLAS helper functions:
  • MuonIdHelperSvc instead of manual station selection
  • xAODP4Helpers

New functionality:

• Global cartesian position of Tracklets
• Linking Tracklets to vertices

@jojungge, @obrandt, @mireveri