R34 Jona: Improvements ROI & POI Visualization

POI

• Always show main marker (was previously hidden when dragged)
• Add delete button
• Add 'delete all' button

ROI (new roi_visualization node)

• Add transparent ROI marker with different colors depending on ROI type
• Split delete buttons
  • One button deletes by unique ROI ID
  • One button deletes all ROIs with the same name
  • One button deletes all ROIs