0028416: Visualization - SelectMgr_SelectionManager::Activate() should not implicitly...

0028416: Visualization - SelectMgr_SelectionManager::Activate() should not implicitly deactivate Global Selection Mode

Implicit deactivation of global selection mode has been removed from SelectMgr_SelectionManager::Activate().

Added new method AIS_InteractiveContext::SetSelectionModeActive() as replacement
of AIS_InteractiveContext::Activate() / ::Deactivate().
New method takes an argument AIS_SelectionModesConcurrency which defines
what to do with already activated selection modes in 3 ways:
- AIS_SelectionModesConcurrency_Single, only one selection mode can be activated at
  the same moment - previously activated should be deactivated
- AIS_SelectionModesConcurrency_GlobalOrLocal, either Global (AIS_InteractiveObject::GlobalSelectionMode()
  or Local (multiple) selection modes can be active at the same moment
- AIS_SelectionModesConcurrency_Multiple, any combination of selection modes can be activated.