Add support for nested images to LLava and VipLLava (#35558)

* move make_flat_list_of_images and make_batched_videos to image_utils

* remove unnecessary is_vision_available

* move make_nested_list_of_images to image_utils

* fix fast pixtral image processor

* fix import mllama

* fix make_nested_list_of_images

* add tests

* convert 4d arrays/tensors to list

* add test_make_batched_videos

* add support nested batch of videos

* fix image processing qwen2vl

tests/models/pixtral/test_modeling_pixtral.py

@@ -20,7 +20,6 @@ from transformers import (
     PixtralVisionConfig,
     PixtralVisionModel,
     is_torch_available,
-    is_vision_available,
 )
 from transformers.testing_utils import (
     require_torch,
@@ -35,10 +34,6 @@ if is_torch_available():
     import torch
 
 
-if is_vision_available():
-    pass
-
-
 class PixtralVisionModelTester:
     def __init__(
         self,