[Trainer] Allow passing image processor (#29896)

* Add image processor to trainer

* Replace tokenizer=image_processor everywhere

examples/pytorch/semantic-segmentation/run_semantic_segmentation.py

@@ -510,7 +510,7 @@ def main():
         train_dataset=dataset["train"] if training_args.do_train else None,
         eval_dataset=dataset["validation"] if training_args.do_eval else None,
         compute_metrics=compute_metrics,
-        tokenizer=image_processor,
+        image_processor=image_processor,
         data_collator=default_data_collator,
     )