text: Title: Add BoundingBoxes class information 
  Body: ### 🚀 The feature
  
  Another meta field which includes the index of the corresponding class of the BoudingBox.
  
  ### Motivation, pitch
  
  At the moment, I need to carry the class indices of the BoundingBoxes separate. This leads to the issue, that I need to carry it around everywhere I need to access the bbox.
  
  Additional when creating a BBox the class creation method (__init__/__new__?) can guard against wrong shapes, if this optional feature is used. 
  
  ### Alternatives
  
  _No response_
  
  ### Additional context
  
  _No response_