OwlViT/Owlv2 post processing standardization (#34929)
* Refactor owlvit post_process_object_detection + add text_labels
* Fix copies in grounding dino
* Sync with Owlv2 postprocessing
* Add post_process_grounded_object_detection method to processor, deprecate post_process_object_detection
* Add test cases
* Move text_labels to processors only
* [run-slow] owlvit owlv2
* [run-slow] owlvit, owlv2
* Update snippets
* Update docs structure
* Update deprecated objects for check_repo
* Update docstring for post processing of image guided object detection
