Add GiGaEventActionCommand and refactor GiGaRunActionCommand + UI session

GiGaRunActionCommand:

• moving it from the library,
• collapsing all in one cpp file,
• additional refatoring,

GiGaRunActionCommand:

• ported from Gauss,
• adapted to the factory-style GiGa interface in Gaussino,
• additional refactoring
• commands are accessible from SimPhase as G4BeginEventCommand and G4EndEventCommand

FYI @fbilandz (this is needed to run visualization with Geant4 using its UI)

Update 05/08/22 support for interactive UI session added, now needs !70